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76 Cards in this Set

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1. A pre-surgical drug that produces skeletal muscle relaxation by blocking the subtype of nicotinic receptors expressed at the skeletal muscle neuromuscular junction (NMJ):
A. atropine
B. ipratropium
C. pralidoxime
D. scopalamine
E. tubocurarine
Answer: E. tubocurarine. Atropine, ipratropium and scopolamine are antimuscarinics (and thus have no effect on nicotinic receptors) and pralidoxime is a cholinesterase “reactivator”
2. This drug produces a dilated pupil that is unresponsive to light.
A. atropine
B. ephedrine
C. imipramine
D. phenylzine
E. tyramine
Answer: A. atropine. This “belladona alkaloid” will produce mydriasis and cycloplegia
3. MJ is a 5 year old Golden Retriever that was admitted with an initial complaint of a 24 hr history of confusion. On examination the patient was febrile, had tachycardia, his mucous membranes and skin had an unusual ‘flush” color and his pupils were dilated. His owners also indicated that he had been consuming an extraordinary amount of water over the past 24 hr. Upon further questioning, it was determined that MJ had recently consumed berries growing on a wild shrub along the back border of the fenced-in yard to which the dog had access. The most likely active ingredient in these berries is:
A. atropine
B. pilocarpine
C. reserpine
D. tyramine
E. ephedrine
Answer: A. atropine. The other drugs produce distinctly different toxicity. This patient’s symptoms resemble the toxicity of belladonna alkaloids and the berries shown are from the “nightshade shrub” (Atropa belladonna). The symptoms of antimuscarinic toxicity resemble the phrase: “Blind as a Bat, Mad as a Hatter, Red as a Beet, Dry as a Bone, Hot as Hell”.
4. A drug that could be used to reverse MJ’s symptoms related to belladonna toxicity is:
A. physostigmine
B. pralidoxime
C. scopolamine
D. succinylcholine
E. tubocurarine
Answer: A. Physostigmine reverses the effects of drugs that cause an anticholinergic syndrome. Physostigmine is an anti-cholinesterase. Inhibition of cholinesterase increases the amount of acetylcholine (ACh) in the synaptic cleft. ACh competes with atropine (which is a competitive muscarinic antagonist) for binding to the muscarinic receptor. Increasing ACh levels increases the probability of ACh-receptor binding.
5. A 10 year-old Labrador retriever undergoes radiotherapy to treat a tumor in the neck region. A side effect of this therapy is the development of salivary gland hypofunction, with associated dry mouth. An agent that could be used to treat this patient’s condition is:
A. atropine
B. ipratropium
C. nicotine
D. pilocarpine
E. scopalamine
Answer: D. Pilocarpine. Pilocarpine (a muscarinic agonist) is indicated for this patient’s condition. However, it should not be used in patients with uncontrolled asthma or narrow angle (angle closure) glaucoma (why?). Atropine, scopolamine and ipratropium are muscarinic antagonists that would worsen this patient’s condition. Nicotine is a nicotinic agonist.
6. Which of the following ACh-like compounds is selective for muscarinic receptors and resistant to degradation by acetylcholinesterase?
A. bethanechol
B. echothiophate
C. physostigmine
D. methacholine
E. carbachol
Answer: A. bethanachol. Echothiophate is an organophosphate anti-cholinesterase. Physostigmine is a cholinesterase inhibitor. Methacholine is also selective for muscarinic receptors but can be hydrolyzed by acetylcholinesterase.
7. A long acting organophosphate inhibitor of acetylcholinesterase that is used in topical eye drops to cause contraction of the ciliary body, which facilitates the outflow of aqueous humor, is
A. edrophonium
B. echothiophate
C. physostigmine
D. pyridostigmine
E. pilocarpine
Answer: B. echothiophate. Just as “echo” is a prolonged sound, ‘echo’thiophate is a long-acting anti-cholinesterase. In contrast, “Ed” is a short name and ‘ed’rophonium is a short acting (carbamate) inhibitor of cholinesterase. Physostigmine and pyridostigmine are also carbamates with other indications; pilocarpine is a muscarinic agonist.
8. Trimethaphan (which is a NN antagonist similar to hexamethonium) administered i.v. will produce:
A. bradycardia
B. increased GI motility
C. vasoconstriction and hypertension
D. vasodilation and hypotension
E. vomiting
Answer: D. vasodilation and hypotension. Trimethaphan is a ganglionic blocker indicated for the treatment of dissecting aortic aneurysms and hypertensive emergencies where you need to rapidly lower blood pressure and maintain it at lower levels for some time. Ganglionic blockers ‘reverse’ predominant tone, whether it is sympathetic or parasympathetic. In most organ systems, predominant tone is parasympathetic. The arterioles are the exception to that rule. Bradycardia, increased GI motility and vomiting can be produced by increased
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muscarinic stimulation and would not be produced by a ganglionic blocker. Vasoconstriction and hypertension are the responses opposite to those expected by removing sympathetic tone to the arteries.
9. An older dog undergoes intra-abdominal surgery. During post-operative recovery, she develops constipation and abdominal discomfort due to GI stasis, which can result from surgical manipulation of the intestines. Which of the following could be given to best treat her condition?
A. Ipratropium
B. Neostigmine or Physostigmine
C. Hemicholinium
D. Scopolamine
E. Tubocurarine
Answer: B. Neostigmine or Physostigmine. The cholinesterase inhibiting actions of these drugs will increase parasympathetic tone to the GI tract and increase peristalsis. It is also used to treat myasthenia gravis. [Note: neostigmine may be preferred over physostigmine for these indications because it is a quarternary drug that does not cross the BBB and produce unwanted CNS effects]. Ipratropium and scopolamine are anti-muscarinic agents which would only exacerbate the problem. Tubocurarine is a nicotinic antagonist that selectively blocks neurotransmission at the neuromuscular junction.
10. Dairy cattle are accidentally left to graze in a field recently sprayed heavily with organophosphate pesticide to control intense infestation of the grasses with chewing insects. Which of the following describes symptoms likely to be observed in acutely intoxicated animals?
A. dilated pupils
B. extreme thirst, blindness
C. red mucous membranes, elevated body temperature
D. salivation, urination, diarrhea
E. blind staggers
Answer: D. salivation, urination, diarrhea. These are some of the DUMBELS symptoms.
11. Which of the following two drugs could you use to reverse the symptoms seen in OP-intoxicated cattle?
A. atropine
B. physostigmine
C. pilocarpine
D. pralidoxime
E. hexamethonium (ganglionic blocker)
Answer: A. atropine and D. pralidoxime. The other drugs, such as neostigmine (carbamate cholinesterase inhibitor) or pilocarpine (muscarinic agonist) would make the symptoms worse, and hexamethonium (ganglionic blocker) would do as much harm as good by also blocking sympathetic neurotransmission.
12. A dog from a line with a history of myasthenia gravis develops muscle weakness around the eyes and tires quickly after activity but improves with rest. In addition to blood tests for elevated antibodies, you administer a drug to help confirm the diagnosis that the symptoms are due to myasthenia gravis. If the diagnosis is correct, it will produce a transient reversal of the patient’s symptoms. The drug you administer is:
A. echothiophate
B. edrophonium
C. pilocarpine
D. succinylcholine
E. tubocurarine
Answer: B. edrophonium. “Ed” is a short acting carbamate cholinesterase inhibitor that would produce an immediate relief of symptoms of myasthenia gravis. If the patient’s conditions were caused by another abnormality, the patient would not respond. Echothiophate is a long-lasting organophosphate used in eye drops to treat glaucoma. Pilocarpine is a muscarinic agonist that would have no effect on skeletal muscle. Tubocurarine and succinylcholine would paralyze your patient!
13. Your patient with myasthenia gravis requires chronic treatment for relief of muscle weakness. A drug that would be a good choice for maintenance therapy, and which would not cross the BBB is:
A. pilocarpine
B. atropine
C. neostigmine
D. physostigmine
E. pralidoxime
Answer: C. neostigmine. Neostigmine is a long-lasting cholinesterase inhibitor that does not cross the BBB. Physostigmine, also a cholinesterase inhibitor, crosses the BBB to reach the CNS and thus would produce unwanted side effects (it is used for treating overdose by anti-muscarinic agents). Pilocarpine is a muscarinic agonist and atropine a muscarinic antagonist, therefore, neither has effects at the neuromuscular junction. Pralidoxime is used to regenerate AChE following acute OP intoxication.
14. You are treating a cat with intermittent asthmatic symptoms who cannot tolerate the side effects (CNS stimulation) of his inhaled short acting beta-2 agonist. Therefore, you recommend that he try an inhaled anti-muscarinic to see if that works better for him. You prescribe:
A. atropine
B. ipratropium
C. neostigmine
D. scopolamine
E. tiotropium
Answer: E. Tiotropium. Tiotropium and ipratropium are quaternary drugs that are not well absorbed and thus remain localized to lung tissue when inhaled. Tiotropium is a selective M3 receptor antagonist and thus blocks only muscarinic receptors on the airway smooth muscle. In contrast, ipratropium antagonizes both M2 and M3 receptors and blocks not only muscarinic receptors on airway smooth muscle, but also autoinhibitory M2 receptors on parasympathetic nerve terminals (which increases the amount of ACh available to bind to airway smooth muscle). Atropine and scopolamine are not available as inhaled formulations for asthma and are readily absorbed, causing significant side effects. Neostigmine, a cholinesterase inhibitor, would make asthma worse.
15. Your patient is recovering from abdominal surgery and develops post-operative urinary retention. A drug that you could give orally to treat this condition is:
A. atropine
B. bethanechol
C. prazosin
D. succinylcholine (muscle relaxant)
E. tubocurarine
Answer: B. bethanechol. Bethanechol is a muscarinic agonist indicated for this situation. It can increase the tone of the detrusor muscle sufficiently to initiate micturition and help empty the urinary bladder. In contrast, atropine and scopolamine are muscarinic antagonists that would not be useful. Neither would the skeletal muscle relaxants that act on the skeletal muscle isoform of nicotinic receptors (succinylcholine and tubocurarine).
16. The enzyme that is rate-limiting in the synthesis of norepinephrine from dietary tyrosine is:
A. aromatic amino acid decarboxylase
B. dopamine beta hydroxylase
C. monoamine oxidase
D. phenylethanolamine N-methyltransferase
E. tyrosine hydroxylase
Answer: E. tyrosine hydroxylase. This is the enzyme inhibited by alpha-methyltyrosine to cause sympatholytic effects.
17. An adrenergic receptor subtype expressed in airway smooth muscle of all species that is not functionally innervated by the sympathetic nervous system in many species, but is stimulated by circulating epinephrine released by the adrenal medulla under “fight or flight” conditions to produce bronchodilation is:
A. α1
B. α2
C. β1
D. β2
E. β3
Answer: D. β2. The expression of these receptors on airway smooth muscle is also the reason that short acting β agonist, such as albuterol and terbutaline are effective in clinical management of acute asthmatic attack.
18. The primary mechanism of terminating the action of released norepinephrine is:
A. diffusion from the synapse
B. Uptake 1 (via NET or norepinephrine transporter)
C. MAO
D. COMT
E. VMAT
Answer: B. Uptake 1. NET, which mediates Uptake 1, or uptake into the presynaptic terminal, is responsible for terminating the action of ~ 75% of the released norepinephrine. The remaining 25% is removed by extracellular COMT and diffusion. MAO cannot terminate the action of “released” NE because it is in the mitochondria; MAO can metabolize cytoplasmic NE within the presynaptic nerve terminal.
19. Circulating catecholamines, including injected epinephrine and norepinephrine (or drugs with agonist activity at the appropriate adrenergic receptor subtype) can stimulate which non-synaptic receptor subtype expressed in vascular smooth muscle to produce a rise (increase) in arterial blood pressure:
A. α1
B. α2
C. β1
D. β2
E. β3
Answer: B. α2. Alpha-2 receptors on vascular smooth muscle are not directly innervated by sympathetic nerves (similar to β2 receptors on vascular smooth muscle) and thus are only stimulated by circulating catecholamines or α2 agonists delivered systemically (Note: this is NOT an exception to the “rule” that α2 receptors are typically presynaptic because there is not a synapse expressed at these sites in the vascular smooth muscle). When stimulated, these non-synaptic α2 receptors produce a vasoconstriction. The β2 receptors found in vascular smooth muscle of skeletal muscle beds are also not functionally innervated, but these produce a
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vasodilation in skeletal muscle beds when stimulated. Alpha-1 receptors on vascular smooth muscle are directly innervated by sympathetic nerves and produce vasoconstriction in response to NE released from the presynaptic sympathetic nerve terminal.

Note: contrast this to question 39 (below) that indicates that Amitraz, an α2 agonist in Preventic collars causes profound hypotension and bradycardia. Amitraz (and xylazine and clonidine) are selective α2 agonists (they do NOT activate α1 receptors), unlike the circulating catecholamines that activate both α1 and α2 receptors. The few non-synaptic α2 receptors located on blood vessels that are activated by α2 agonists are not sufficient to counteract the profound inhibition of presynaptic release of NE by activation of autoinhibitory α2 receptors.
20. An adrenergic receptor subtype expressed on vascular smooth muscle that is typically not functionally innervated by the sympathetic nervous system but is stimulated by circulating epinephrine released by the adrenal medulla under “fight or flight” conditions to produce vasodilation in skeletal muscle is:
A. α1
B. α2
C. β1
D. β2
E. β3
Answer: D. β2. β2 receptors expressed on the vascular smooth muscle in skeletal muscle are not directly innervated. When activated by catecholamines (or by β2 agonists), they cause relaxation of vascular smooth muscle, or vasodilation. There are also “non-synaptic” α2 receptors in resistance vesicles that respond to circulating catecholamines, producing vasoconstriction.
21. A drug used both as a nasal decongestant, and as a pressor agent (e.g. to cause vasoconstriction) to correct surgically induced hypotension without the risk of epinephrine-induced arrhythmias:
A. bretylium (blocks release of norepinephrine from nerve terminals)
B. isoproterenol
C. phenoxybenzamine
D. phenylephrine
E. prazosin
Answer: D. phenylephrine. Phenylephrine is an α1 agonist. Isoproterenol would decrease blood pressure. The other drugs would not produce the desired response.
22. A catecholamine that when given i.v. in moderate doses will produce the relatively largest increase in heart rate and cardiac output:
A. epinephrine
B. isoproterenol
C. norepinephrine
D. dopamine
E. phenylephrine
Answer: B. isoproterenol. Isoproterenol produces both direct stimulation of cardiac β1 receptors and a reflex-mediated sympathetic stimulation of cardiac β1 receptors as a result of its effect to lower the mean arterial blood pressure in response to stimulating β2 receptors in skeletal muscle. It has low affinity for α1 receptors so does not cause significant vasoconstriction via activation of these receptors.
23. A selective β1 agonist that is used to produce short term positive ionotropic support in patients in cardiogenic shock, or with acute heart failure.
A. sotalol
B. dobutamine
C. dopamine
D. epinephrine
E norepinephrine
Answer: B. Dobutamine. Dobutamine is the only drug listed that is a selective β1 agonist.
24. In the presence of a drug with α blocking activity, injection of epinephrine will produce a change in arterial blood pressure resembling that produced by:
A. atenolol
B. norepinephrine
C. isoproterenol
D. propranolol
E. phenylephrine
Answer: C. isoproterenol. Epinephrine is an agonist for α1 and α2 receptors as well as β1 and β2 receptors. Blocking α receptors will make epinephrine’s effect resemble that of isoproterenol, which is a β1 and β2 agonist. Atenolol is a selective β1 antagonist; norepinephrine activates α1 and β1 receptors; propranolol is a non-selective β antagonist (blocks both β1 and β2 receptors); phenylephrine is an α1 agonist.
25. You are working in the ER when a patient arrives with symptoms of an asthmatic attack including wheezing and difficulty breathing. A drug that can be administered by inhalation for acute relief of this patient’s symptoms is:
A. albuterol
B. bethanechol
C. phenylephrine
D. propranolol
E. sotalol
Answer: A. albuterol. Albuterol and terbutaline are short acting β2-selective agonists that produce a maximal effect on relaxation of airway smooth muscle (bronchodilation) within 15-30 minutes after inhalation. Bethanechol is a muscarinic agonist that would worsen bronchoconstriction; phenylephrine is an α1 agonist that would not affect airway smooth muscle; propranolol and sotalol are non-selective β antagonists that would worsen bronchoconstriction.
26. During fight or flight conditions, circulating epinephrine released from the adrenal medulla will:
A. constrict skeletal muscle arterioles
B. decrease the pain threshold
C. inhibit lipolysis
D. produce miosis
E. stimulate glycogen breakdown
Answer: E. stimulate glycogen breakdown. Circulating epinephrine will do the opposite of the other options listed in A through D.
27. A patient arrives in the ER suffering from anaphylactic shock including difficulty breathing, severe urticaria (hives) and hypotension. Which of the following is the drug of choice for treating this patient’s potentially life-threatening condition?
A. epinephrine
B. isoproterenol
C. norepinephrine
D. phenylephrine
E. albuterol
Answer: A. epinephrine. Parenteral administration of epinephrine is the best choice. In this situation you need a drug that has BOTH beta-2-mediated bronchodilator effects and alpha-mediated pressor effects. Its vasoconstrictive effects on bronchial blood vessels may also reduce bronchial fluid congestion.
28. Match the drug with the most likely adverse reaction to be caused by that drug:
Ephedrine (α1 agonist)
Brimonidine (α2 agonist)
Phenoxybenzamine (α antagonist)
OP pesticide
Bethanechol
Amphetamine
Atropine
Vincristine

ADVERSE RXNS
Blurred vision (mydriasis)
Peripheral neuropathy
Depolarizing blockade at neuromuscular junction
Abdominal cramps
Postural hypotension
Hypertension
Tachycardia
Bradycardia
Correct matches:
Ephedrine (α1 agonist: Hypertension (vasoconstriction)
Brimonidine (α2 agonist): Bradycardia (presynaptic inhibition of NE release; note: OP pesticide might also have this effect)
Phenoxybenzamine (α antagonist): Postural hypotension (block of vasoconstriction)
OP pesticide: Depolarizing blockade at neuromuscular junction (OPs are only agents on this list that affect nicotinic receptors at NMJ)
Bethanechol: Abdominal cramps (muscarinic agonist; OP pesticide could also cause this)
Amphetamine: Tachycardia (because of NE release from presynaptic terminals)
Atropine: Blurred vision (mydriasis)
Vincristine: Peripheral neuropathy (microtubule disrupting agent that interferes with axonal transport)
29. Match the condition with the most likely pharmacotherapy:
Epinephrine
Phenylephrine
Dobutamine
Albuterol
Prazosin
Bethanechol
Neostigmine
Scopolamine

PHARMACOTHERAPY:
Hypertension
GI stasis and urinary retention (in the absence of obstruction)
Cardiac arrest
Anaphylaxis
Asthmatic attack
Myasthenia gravis
Prevent reflex- or drug-induced bradycardia during surgery
Nasal decongestant
Correct matches:
Epinephrine Anaphylaxis
Phenylephrine Nasal decongestant
9
Dobutamine Cardiac arrest
Albuterol Asthmatic attack
Prazosin Hypertension
Bethanechol GI stasis and urinary retention (in the absence of obstruction)
Neostigmine Myasthenia gravis
Scopolamine Prevent reflex- or drug-induced bradycardia during surgery
30. Which of the following agents is NOT a sympathomimetic neurotoxicant?
A. Methamphetamine
B. Cocaine
C. Reserpine (blocke NE transport into synaptic vesicles)
D. Theobromine (active ingredient in chocolate)
E. Pseudoephedrine
Answer: C. Reserpine. All of these agents can have neurotoxic effects in the ANS, but unlike the other agents in the list, botulinum toxin mediates its neurotoxic effects by blocking sympathetic neurotransmission. Reserpine blocks the transport of NE into synaptic vesicles in the presynaptic terminal. (How do the other agents work to mimic or increase sympathetic neurotransmission?)
31. Administration of a moderately high dose of epinephrine to a patient results in an unexpected severe decrease in blood pressure. Which of the following drugs might the patient have been previously administered that could account for this unexpected effect?
A. cocaine
B. atropine
C. sotalol
D. prazosin
E. phenylephrine
Answer: D. prazosin. Prazosin is an alpha-1 receptor antagonist and thus blocks the direct vasoconstrictor response to epinephrine. Phenylephrine is an alpha-1 receptor agonist so would be expected to augment the vasoconstrictor effect of epinephrine; cocaine can block neuronal uptake of NE and will not interfere with the vasoconstrictor effect of epinephrine; atropine is a muscarinic receptor antagonist and will not interfere with the vasoconstrictor response of epinephrine; sotalol is a non-selective β antagonist so would be expected to block the vasodilating effects of epinephrine.
32. A drug that stimulates beta1 and beta2 adrenergic receptors can be expected to cause:
A. a decrease in heart rate
B. a decrease in total peripheral resistance (aka decreased blood pressure)
C. a constriction of airway smooth muscle
D. an increase in release of ACh from postganglionic parasympathetic nerves
E. none of the above
Answer: B. a decrease in total peripheral resistance. Beta-2 receptor activation will relax vascular smooth muscle and reduce blood pressure. Heart rate would be stimulated directly (by beta1 receptor activation) and reflexively (by beta2 receptor activation); beta2 receptor activation relaxes bronchial smooth muscle; beta2 receptor activation decreases release of ACh from postganglionic parasympathetic nerves.
33. Which of the following drugs is the shortest acting acetylcholinesterase inhibitor?
A. Neostigmine
B. Physostigmine
C. Edrophonium
D. Echothiophate
E. tropicamide
Answer: C. Edrophonium. Edrophonium has a short duration of action, 5-15 min, thus it is used for diagnosis of myasthenia gravis; neostigmine and physostigmine are reversible inhibitors whose effects last for 30 min- 2 hr; echothiophate is a long-lasting inhibitor, greater than 100 hours, and thus is useful for long-term treatment, such as in glaucoma. Tropicamide is a muscarinic antagonist.
34. Poisoning with OP pesticides is best managed by administration of which of the following agents?
A. Physostigmine
B. Bethanechol
C. Propranolol
D. Pilocarpine
E. Atropine
Answer E. Atropine. Atropine blocks the muscarinic effects of increased ACh resulting from cholinesterase inhibition. Physostigmine is a cholinesterase inhibitor, which would exacerbate the situation; Bethanechol and pilocarpine are both muscarinic agonists, which would also make the situation worse; propranolol is a beta blocker, so would be ineffective in treating effects due to too much acetylcholine in the synaptic cleft.
35. Receptor actions of acetylcholine are mimicked by nicotine at which of the following sites?
A. Adrenal medullary chromaffin cells
B. Urinary bladder smooth muscle cells
C. Iris constrictor muscle
D. Postganglioinc sympathetic neurons
E. More than one of the above
Answer: E. More than one of the above. Nicotinic receptors are expressed on the adrenal medullary chromaffin cells and on postganglionic sympathetic neurons.
36. Which of the following drugs would decrease release of norepinephrine from sympathetic neurons?
A. Prazocin
B. Phenylephrine
C. Botulinum toxin
D. Clonidine (α2 agonist)
E. More than one of the above
Answer: E. Clonidine. Clonidine is an alpha2 receptor agonist. Activation of presynaptic alpha2 receptors decreases NE release from sympathetic neurons. Prazocin is an alpha1 receptor antagonist; atropine is a muscarinic receptor antagonist; Botulinum toxin blocks presynaptic release of acetylcholine at neuromuscular junction; phenylephrine is an alpha1 receptor agonist.
37. Muscarinic receptor agonists can induce vasodilation by causing the release of endothelial:
A. Histamine
B. Norepinephrine
C. Acetylcholine
D. Nitric oxide
E. None of the above
Answer: D. Nitric oxide. Parasympathetic nerves do not innervate vascular smooth muscle, but they do innervate endothelial cells of blood vessels in some vascular beds. Activation of muscarinic receptors on endothelial cells causes release of nitric oxide (NO), which is a potent vasodilator.
38. Which of the following agents would be most likely to cause bronchial dilation?
A. Phenylephrine
B. Clonidine
C. Dobutamine
D. Atenolol
E. Tiotropium
Answer: E. Tiotropium. Tiotropium is a selective M3 receptor antagonist. M3 receptors are expressed on airway smooth muscle, and binding of ACh to these receptors causes bronchoconstriction. Phenylephrine is an α1 agonist, clonidine is an α2 agonist, dobutamine is a selective β1 receptor agonist and atenolol is a β1 receptor antagonist.
39. The active ingredient in Preventic collars, Amitraz, is an α2 agonist. Ingestion of these collars can cause profound hypotension and bradycardia. These symptoms would be best treated by administration of:
A. yohimbine
B. ephedrine
C. clonidine
D. bethanechol
E. xylazine
Answer: A. Yohimbine. Yohimbine is an α2 antagonist, so it counteracts the agonistic effects of Amitraz at the α2 receptor. Ephedrine is an α1 agonist, so it might be helpful in reversing the hypotension caused by Amitraz, but is unlikely to be effective in reversing the bradycardia. Clonidine and xylazine are both α2 agonists like Amitraz. Bethanechol, a muscarinic agonist would likely exacerbate the effects of Amitraz on HR.
40. At low doses, ipratropium may actually exacerbate airway hyperreactivity via:
A. activation of presynaptic M2 receptors expressed on parasympathetic nerves
B. activation of postsynaptic M3 receptors expressed on airway smooth muscle
C. inhibition of presynaptic M2 receptors expressed on parasympathetic nerves
D. inhibition of postsynaptic M3 receptors expressed on airway smooth muscle
E. more than one of the above
Answer: C. inhibition of presynaptic M2 receptors expressed on parasympathetic nerves. Ipratropium is a non-selective muscarinic antagonist (inhibits all muscarinic receptors), but it preferentially inhibits M2 receptors at lower doses (M3 receptor antagonism is only observed at higher doses of ipratropium). M2 receptors on presynaptic parasympathetic neurons function to decrease ACh release from parasympathetic nerves. Inhibition of these M2 receptors thus removes this negative feedback loop, resulting in increased levels of ACh released into the synaptic cleft, which increases bronchoconstriction by increasing activation of M3 receptors on the airway smooth muscle.
41. The primary mechanism by which organophosphorus pesticides (OPs) cause acute toxicity is inhibition of acetylcholinesterase. However, OPs can cause airway hyperreactivity at levels that do NOT cause significant inhibition of acetylcholinesterase. The primary mechanism mediating this effect is:
A. Activation of M3 receptors on airway smooth muscle
B. Activation of M2 receptors on presynaptic parasympathetic neurons
C. Activation of M2 receptors on presynaptic sympathetic neurons
D. Inactivation of M3 receptors on airway smooth muscle
E. Inactivation of M2 receptors on presynaptic parasympathetic neurons
Answer: E. Inactivation of M2 receptors on presynaptic parasympathetic neurons.
42. Which of the following neurotoxins interfere with neurotransmission in both the parasympathetic and sympathetic nervous systems?
A. Amanita mushroom (muscarine)
B. Atropa belladonna (atropine)
C. Nicotine
D. Datura stramonium (scopolamine)
E. More than one of the above
Answer: E. More than one of the above. In both the sympathetic and parasympathetic nervous systems, transmission across the ganglionic synapse is mediated by release of ACh from the presynaptic preganglionic neuron that binds to nicotinic receptors on the postsynaptic postganglionic neurons, thus nicotine will interfere with neurotransmission at ganglionic synapses in both sympathetic and parasympathetic nervous systems. The other neurotoxins are all muscarinic agonists or antagonists, and thus they interfere with neurotransmission between postganglionic parasympathetic neurons and their effector targets, and between sympathetic neurons and sweat glands. While MOST neurotransmission in the sympathetic nervous system is mediated by NE, sympathetic neurons that innervate sweat glands synthesize and release ACh, which binds to muscarinic receptors on the sweat glands.
43. Which of the following agents blocks the release of neurotransmitter from the presynaptic nerve terminal?
A. Cocaine
B. Amphetamine
C. Theobromine
D. Botulinum toxin
E. Tubocurarine
Answer: D. Botulinum toxin. What is the mechanism of action of the other agents?
44. A 6-month old puppy is brought to the VMTH after his owners discover that she has accidentally punctured the pressurized inhaler used to treat their son when he has an asthmatic attack. The puppy initially presents with profound hypotension which is followed by reflex tachycardia. Your best treatment option would be:
A. Albuterol
B. Propranolol
C. Isoproterenol
D. Dobutamine
E. Prazosin
Answer: B. Propranolol. The active ingredient in pressurized inhalers used in treatment of asthmatic attacks is typically short acting β2 agonists, such as albuterol or terbutaline. This would be consistent with the symptoms observed in the puppy. A β blocker, particularly a non-selective β blocker that would counteract the vasodilation caused by β2 activation and the tachycardia mediated by β1 activation, would be the best treatment option. The only β blocker on the list is propranolol, and it is a non-selective β blocker. Albuterol is a β2 agonist; isoproterenol activates β1, and β2 receptors; dobutamine is a selective β1 agonist and prazosin is an α1 antagonist (which would cause vasodilation).
45. The direct cardiac effects of dobutamine would be blocked by which of the following agents?
A. Sotalol
B. Atenolol
C. Clonidine
D. Isoproterenol
E. Prazosin
Answer: B. Atenolol. Dobutamine is a selective β1 agonist and atenolol is a selective β1 antagonist. Sotalol is a non-selective β antagonist, clonidine is an α2 agonist, isoproterenol is an α1, β1 and β2 agonist.
46. Topical application of timolol (non-selective β1 antagonist) to the eye would be expected to induce which of the following?
A. Miosis
B. Mydriasis
C. Decreased formation of aqueous humor
D. Increased outflow of aqueous humor
E. More than one of the above
Answer: C. Decreased formation of aqueous humor. Timolol (non-selective beta blocker) is used to treat open-angle and occasionally secondary glaucoma by reducing aqueous humor production through blockage of the beta receptors on the ciliary epithelial cells (the cells that produce aqueous humor). Timolol has no effect on pupil size (so does not change vision).
47. Phenylephrine is applied to nasal mucosa in order to:
A. Block histamine receptors
B. Block β adrenergic receptors
C. Induce vasodilation
D. Induce vasoconstriction
E. Block α adrenergic receptors
Answer: C. Induce vasoconstriction. Phenylephrine is an α1 agonist that causes vasoconstriction of blood vessels in the nasal passages.
48. Which of the following receptor types is NOT a metabotropic receptor?
A. Nicotinic receptors
B. M1, M3 and M5 muscarinic receptors
C. M2 and M4 muscarinic receptors
D. alpha adrenergic receptors
E. beta adrenergic receptors
Answer: A. Nicotinic receptors. Nicotinic receptors are ionotropic receptors, also known as ligand-gated ion channels.
49. The release of acetylcholine from postganglionic sympathetic neurons is responsible for which of the following responses?
A. constriction of cutaneous blood vessels
B. Contraction of piloerector muscles
C. Activation of sweat glands
D. Decreased gastrointestinal motility
E. None of the above because postganglionic sympathetic neurons do not release acetylcholine.
Answer: C. Activation of sweat glands
50. Pinpoint pupils (miosis), coma, profuse sweating, salivation, bronchial hypersecretions, bronchospasm and muscle weakness are most likely due to intoxication by:
A. Jimson weed (belladonna alkaloids)
B. Carbamate pesticides
C. Acepromazine
D. Cocaine
E. Vincristine
Answer: B. Carbamate pesticides. The toxicity profile of carbamate pesticides is very similar to that of OP pesticides because like OPs, carbamates inhibit acetylcholinesterase. The major difference is AChE inhibition by carbamates is reversible; whereas OP inhibition of AChE is often irreversible.
Directions for questions 51-56: For each question, select the ONE agent in the list below that is most closely associated with it. Each agent may be selected once, more than once, or not at all:
A. α1 receptors
B. β1 receptors
C. α2 receptors
D. β2 receptors
E. muscarinic receptors

51. Norepinephrine can act directly on these receptors to increase heart rate.
Answer: B.
Directions for questions 51-56: For each question, select the ONE agent in the list below that is most closely associated with it. Each agent may be selected once, more than once, or not at all:
A. α1 receptors
B. β1 receptors
C. α2 receptors
D. β2 receptors
E. muscarinic receptors

52. Epinephrine acts on these receptors to contract arteriolar smooth muscle
Answer: A (C also correct, but α2 receptors are not predominant receptor subtype expressed on vascular smooth muscle).
Directions for questions 51-56: For each question, select the ONE agent in the list below that is most closely associated with it. Each agent may be selected once, more than once, or not at all:
A. α1 receptors
B. β1 receptors
C. α2 receptors
D. β2 receptors
E. muscarinic receptors

53. Acetylcholine acts on these receptors to increase gastric acid secretion and intestinal motility
Answer: E.
Directions for questions 51-56: For each question, select the ONE agent in the list below that is most closely associated with it. Each agent may be selected once, more than once, or not at all:
A. α1 receptors
B. β1 receptors
C. α2 receptors
D. β2 receptors
E. muscarinic receptors

54. Albuterol acts on these receptors to relax bronchial smooth muscle.
Answer: D.
Directions for questions 51-56: For each question, select the ONE agent in the list below that is most closely associated with it. Each agent may be selected once, more than once, or not at all:
A. α1 receptors
B. β1 receptors
C. α2 receptors
D. β2 receptors
E. muscarinic receptors

55. Norepinephrine stimulates these receptors to decrease release of acetylcholine from parasympathetic nerve
Answer: D.
Directions for questions 51-56: For each question, select the ONE agent in the list below that is most closely associated with it. Each agent may be selected once, more than once, or not at all:
A. α1 receptors
B. β1 receptors
C. α2 receptors
D. β2 receptors
E. muscarinic receptors

56. Autoinhibitory receptors on parasympathetic nerves that when activated by acetylcholine limit further release of acetylcholine.
Answer: E. Muscarinic receptors (M2 specifically)
Directions for questions 57-61: For each question, select the ONE receptor type in the list below that is most closely associated with the action described. Each letter may be selected once, more than once, or not at all:
A. Nicotinic receptors in autonomic ganglia (neuronal nicotinic receptors or NN receptors)
B. Nicotinic receptors in the neuromuscular junction (NM receptors)
C. Nicotinic receptors on adrenal chromaffin cells
D. Muscarinic receptors
E. Adrenergic receptors

57. Activation of this receptor is used in the treatment of glaucoma
Answer: D.
Directions for questions 57-61: For each question, select the ONE receptor type in the list below that is most closely associated with the action described. Each letter may be selected once, more than once, or not at all:
A. Nicotinic receptors in autonomic ganglia (neuronal nicotinic receptors or NN receptors)
B. Nicotinic receptors in the neuromuscular junction (NM receptors)
C. Nicotinic receptors on adrenal chromaffin cells
D. Muscarinic receptors
E. Adrenergic receptors

58. Blockade of this receptor will cause a marked fall in blood pressure
Answer: E. (A also acceptable although decrease in blood pressure not as robust because of mixed effects of ganglionic blockade, e.g., block both sympathetic and parasympathetic)
Directions for questions 57-61: For each question, select the ONE receptor type in the list below that is most closely associated with the action described. Each letter may be selected once, more than once, or not at all:
A. Nicotinic receptors in autonomic ganglia (neuronal nicotinic receptors or NN receptors)
B. Nicotinic receptors in the neuromuscular junction (NM receptors)
C. Nicotinic receptors on adrenal chromaffin cells
D. Muscarinic receptors
E. Adrenergic receptors

59. Blockade of this receptor is used to treat urinary incontinence
Answer: D.
Directions for questions 57-61: For each question, select the ONE receptor type in the list below that is most closely associated with the action described. Each letter may be selected once, more than once, or not at all:
A. Nicotinic receptors in autonomic ganglia (neuronal nicotinic receptors or NN receptors)
B. Nicotinic receptors in the neuromuscular junction (NM receptors)
C. Nicotinic receptors on adrenal chromaffin cells
D. Muscarinic receptors
E. Adrenergic receptors

60. Activation of this receptor is used in treatment of hypotension and shock
Answer: E.
Directions for questions 57-61: For each question, select the ONE receptor type in the list below that is most closely associated with the action described. Each letter may be selected once, more than once, or not at all:
A. Nicotinic receptors in autonomic ganglia (neuronal nicotinic receptors or NN receptors)
B. Nicotinic receptors in the neuromuscular junction (NM receptors)
C. Nicotinic receptors on adrenal chromaffin cells
D. Muscarinic receptors
E. Adrenergic receptors

61. Activation of this receptor is used in treatment of hypotension
Answer: E.
Directions for questions 62-76: For each question, select the letter (A-D) and number (1-2) in the list below that best describe the mechanism of action of the agent identified in the question.
A. Sympathomimetic
B Parasympathomimetic
C. Sympatholytic
D. Parasympatholytic

1. Direct acting
2. Indirect acting

62. Botulinum toxin
Answer: D.2. (prevents release of neurotransmitter from presynaptic terminals – primarily affects peripheral cholinergic nerve terminals)
Directions for questions 62-76: For each question, select the letter (A-D) and number (1-2) in the list below that best describe the mechanism of action of the agent identified in the question.
A. Sympathomimetic
B Parasympathomimetic
C. Sympatholytic
D. Parasympatholytic

1. Direct acting
2. Indirect acting

63. Phenoxybenzamine
Answer: C.1. (non-selective α antagonist)
Directions for questions 62-76: For each question, select the letter (A-D) and number (1-2) in the list below that best describe the mechanism of action of the agent identified in the question.
A. Sympathomimetic
B Parasympathomimetic
C. Sympatholytic
D. Parasympatholytic

1. Direct acting
2. Indirect acting

64. Phenylephrine
Answer: A.1. (α1 agonist)
Directions for questions 62-76: For each question, select the letter (A-D) and number (1-2) in the list below that best describe the mechanism of action of the agent identified in the question.
A. Sympathomimetic
B Parasympathomimetic
C. Sympatholytic
D. Parasympatholytic

1. Direct acting
2. Indirect acting

65. Amphetamine
Answer: A.2. (triggers release of NE from presynaptic terminals)
Directions for questions 62-76: For each question, select the letter (A-D) and number (1-2) in the list below that best describe the mechanism of action of the agent identified in the question.
A. Sympathomimetic
B Parasympathomimetic
C. Sympatholytic
D. Parasympatholytic

1. Direct acting
2. Indirect acting

66 Tubocurarine
Answer: D.1. (blocks nicotinic receptors at the neuromuscular junction)
Directions for questions 62-76: For each question, select the letter (A-D) and number (1-2) in the list below that best describe the mechanism of action of the agent identified in the question.
A. Sympathomimetic
B Parasympathomimetic
C. Sympatholytic
D. Parasympatholytic

1. Direct acting
2. Indirect acting

67. Atropine
Answer: D.1. (non-selective muscarinic antagonist)
Directions for questions 62-76: For each question, select the letter (A-D) and number (1-2) in the list below that best describe the mechanism of action of the agent identified in the question.
A. Sympathomimetic
B Parasympathomimetic
C. Sympatholytic
D. Parasympatholytic

1. Direct acting
2. Indirect acting

68. Prazosin
Answer: C.1. (α1 antagonist)
Directions for questions 62-76: For each question, select the letter (A-D) and number (1-2) in the list below that best describe the mechanism of action of the agent identified in the question.
A. Sympathomimetic
B Parasympathomimetic
C. Sympatholytic
D. Parasympatholytic

1. Direct acting
2. Indirect acting

69. Pilocarpine
Answer: B.1. (muscarinic agonist)
Directions for questions 62-76: For each question, select the letter (A-D) and number (1-2) in the list below that best describe the mechanism of action of the agent identified in the question.
A. Sympathomimetic
B Parasympathomimetic
C. Sympatholytic
D. Parasympatholytic

1. Direct acting
2. Indirect acting

70. Propranolol
Answer: C.1. (non-selective β antagonist)
Directions for questions 62-76: For each question, select the letter (A-D) and number (1-2) in the list below that best describe the mechanism of action of the agent identified in the question.
A. Sympathomimetic
B Parasympathomimetic
C. Sympatholytic
D. Parasympatholytic

1. Direct acting
2. Indirect acting

71. Carbamate pesticides
Answer: B.2.** and A.2. (cholinesterase inhibitor)

**Cholinesterase inhibitors, which include carbamate pesticides and neostigmine in this list, would affect ganglionic synapses in both the sympathetic and parasympathetic nervous systems, all parasympathetic effector synapses, and sympathetic –sweat gland synapses. So, pharmacologically, both A2 and B2 would be correct answers. Clinically, however, the majority of the observed symptoms represent parasympathomimetic effects (notable exception is increased sweating), because the parasympathetic nervous system is the dominant system at most of the affected organ systems
Directions for questions 62-76: For each question, select the letter (A-D) and number (1-2) in the list below that best describe the mechanism of action of the agent identified in the question.
A. Sympathomimetic
B Parasympathomimetic
C. Sympatholytic
D. Parasympatholytic

1. Direct acting
2. Indirect acting

72. Cocaine
Answer: A.2. (blocks uptake NE into presynaptic terminals)
Directions for questions 62-76: For each question, select the letter (A-D) and number (1-2) in the list below that best describe the mechanism of action of the agent identified in the question.
A. Sympathomimetic
B Parasympathomimetic
C. Sympatholytic
D. Parasympatholytic

1. Direct acting
2. Indirect acting

73. Edrophonium
Answer: B.2.** and A.2. (cholinesterase inhibitor)

**Cholinesterase inhibitors, which include carbamate pesticides and neostigmine in this list, would affect ganglionic synapses in both the sympathetic and parasympathetic nervous systems, all parasympathetic effector synapses, and sympathetic –sweat gland synapses. So, pharmacologically, both A2 and B2 would be correct answers. Clinically, however, the majority of the observed symptoms represent parasympathomimetic effects (notable exception is increased sweating), because the parasympathetic nervous system is the dominant system at most of the affected organ systems
Directions for questions 62-76: For each question, select the letter (A-D) and number (1-2) in the list below that best describe the mechanism of action of the agent identified in the question.
A. Sympathomimetic
B Parasympathomimetic
C. Sympatholytic
D. Parasympatholytic

1. Direct acting
2. Indirect acting

74. Bethanecol
Answer: B.1. (muscarinic agonist)
Directions for questions 62-76: For each question, select the letter (A-D) and number (1-2) in the list below that best describe the mechanism of action of the agent identified in the question.
A. Sympathomimetic
B Parasympathomimetic
C. Sympatholytic
D. Parasympatholytic

1. Direct acting
2. Indirect acting

75. Nicotinic NN agonist
Answer: A.1. and B.1.
Directions for questions 62-76: For each question, select the letter (A-D) and number (1-2) in the list below that best describe the mechanism of action of the agent identified in the question.
A. Sympathomimetic
B Parasympathomimetic
C. Sympatholytic
D. Parasympatholytic

1. Direct acting
2. Indirect acting

76. Theobromine
Answer: A.2. (inhibits phosphodiesterase,"", which prolongs signaling via β receptors)