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56 Cards in this Set
- Front
- Back
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Alpha 1 Adrenergic Receptors
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Constriction of vascular smooth muscle
Note: there are many more beta receptors on vascular smooth muscle that lead to vasodilation [that's why an overall sympathetic drive leads to vasodilation] |
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Alpha 2 Adrenergic Receptors
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Auto-inhibition of NE release [present on pre-synaptic adrenergic neurons]
Also leads to constriction [present on post-synpatic locations] |
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Beta 1 Adrenergic Receptors
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Located in the heart [SA node, atria, ventricles, etc.]
Increased HR, contractility, conduction velocity [excitation of the heart] |
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Beta 2 Adrenergic Receptors
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Dilation of airways
dilation of blood vessels auto-stimulation of NE release [opposite of alpha2] - stimulation of beta2 will look like an NE dump! mostly responds to EPI (not by NE as much) most beta2 receptors are non-innervated (makes sense - respond to circulating EPI not NE) |
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Beta 3 Adrenergic Receptors
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Cause lipolysis of brown adipose tissue
also found on the gall bladder and urinary bladder respond well to NE |
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Catecholamines
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naturally occurring chemicals that stimulate adrenergic receptors
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Local Anesthetic Use of EPI
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Local anesthetics [alpha1 peripheral vasoconstriction - will help keep the anesthetic where you want it]
need to be careful with the digits! if EPI gets to the heart - tachycardia! alpha1 peripheral constriction can lead to a spike in peripheral BP leading to a baroreflexive inhibition of the heart (bradycardia) |
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Use of EPI in anaphylactic shock and allergic reactions
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can resolve cardiac collapse
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Use of EPI in bronchial asthma
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dilates the bronchioles through beta 2 receptors
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If you accidently injected yourself with EPI, what would you use to correct it?
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alpha 1 adrenergic antagonist (blocker)
phentolamine is the most common choice |
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Pharmacological uses of Dopamine
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in low doses - dopamine receptor agonist
in high doses - beta adrenergic receptor agonist |
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Veterinary uses of Dopamine
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acute renal failure (questionable)
but it does have diuretic effects and increases perfusion to the kidney |
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Pharmacological uses of Dobutamine
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beta1 adrenergic receptor antagonist (stimulates the generation of cAMP in cells)
has short half-life, but effects last longer because of the generation of cAMP |
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Veterinary uses of Dobutamine
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positive ionotrope in low output congestive heart failure
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Pharmacological uses of Ephedrine
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alpha and beta agonist
elevates HR through beta 1 stimulation (increases BP); weight loss products; nasal decongestant; meth |
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Veterinary uses of Ephedrine
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urinary incontinence (alpha 1 receptors on sphincter)
direct beta stimulant of the heart to help raise BP during anesthesia (in horses) |
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Pharmacological uses of Phenylephrine
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alpha agonist
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Veterinary uses of Phenylephrine
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hypotension and shock (EPI is more commonly used)
pupillary dilation stop epistaxis in dogs (alpha1 vasoconstriction) |
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What is albuterol?
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a beta2 agonist (for bronchodilation)
used as an inhaler |
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What is clenbuterol?
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a beta2 agonist (for bronchodilation)
used a lot with horses (COPD/Heaves) also has beta 3 effects (banned in racing horses and in the NCAA for women athletes) |
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What is terbutaline?
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beta2 agonist (for bronchodilation)
tablet form in cats |
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What is propanalol?
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beta1 antagonist (decrease BP - block sympathetic stimulation of the heart)
wheezing is a side effect from bronchoconstriction |
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What is atenolol?
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beta1 antagonist (decreases BP - block sympathetic stimulation of the heart)
wheezing is a side effect from bronchoconstriction more specific for beta1 receptors than propanalol, so it is used more often |
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What is phenoxybenzamine?
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alpha1 and alpha2 antagonist
decreases urethral sphincter tone laminitis (questionable) used with pheochromocytoma to save the peripheral circulation from constriction (the tumor secretes excess EPI) |
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What is phentolamine?
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alpha1 and alpha2 antagonist
used to save EPI injected digits! and in pheochromocytoma (tumor causes an excess of EPI - this drug prevents peripheral constriction) |
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What is prazosin?
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mostly alpha1 antagonist (some alpha2)
used to treat systemic hypertension |
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What is the baroreflex?
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when we do anything that leads to peripheral constriction of the vasculature, it causes a spike in BP. This reflex responds to that spike by inhibiting the heart (through the vagus nerve / parasympathetic system)
causes a deceleration of the heart can be strong enough to stop the heart |
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Parasympathetic innervation of the bladder comes from what nerve?
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pelvic nerve from the sacral spinal cord
innervates the bladder muscle |
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Sympathetic innervation of the bladder comes from what nerve?
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Hypogastric nerve
innervates the bladder muscle, internal sphincter, and the parasympathetic ganglion [to inhibit the parasympathetic system] |
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How does Urecholine (muscarinic cholinergic agnoist) affect the bladder?
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causes the upper and lower body of the bladder to constrict [via the parasympathetic system]
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How does methoxamine (alpha adrenergic agonist) effect the urinary bladder?
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causes contraction of the mid bladder and upper base of the bladder (via the sympathetic system)
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How does Isoproterenol (beta adrenergic agonist) effect the urinary bladder?
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causes relaxation of the bladder, specifically the lower bod and mid bladder (vai the sympathetic system)
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What system affects the internal sphincter tone of the urinary bladder?
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Sympathetic via alpha1 adrenergic receptors (causes contraction of the sphincter)
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What system predominates during bladder filling? [external sphincter contracted -> stimulation of nicotinic AChR]
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sympathetic system predominates
- internal sphincter contracts (alpha1) - base of bladder contracts (alpha1) - body of bladder relaxes (beta2) - also innervates the parasymp. ganglion, further inhibiting this system |
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What system predominates during bladder emptying? [external sphincter relaxes -> no stimulation of nicotinic AChR]
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Parasympathetic predominates
- body of bladder contracts (muscarinic AChR) - external sphincter relaxes (no stimulation of nicotinic AChR) withdrawal of sympathetic outflow - bladder will contract (loss of beta2 stimulation) - loss of symp. innervation of the parasymp. ganglion - further stimulating the parasympathetic drive |
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What are the 4 common causes of urinary incontinence?
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hormonal deficiencies (estrogen)
- dogs can have a problem after spaying; after the withdrawal of estrogen, the sphincter has trouble contracting as much; doesn't respond as well to NE neurological dysfunction ectopic ureters obstructions |
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How is Oral Diethylstilbestrol (DES) used to treat urinary incontinence?
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hormone replacement for estrogen
was pulled off the human market for side effects - not an issue in dogs, but don't use with pregnant dogs |
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How is Phenylpropanolamine (PPA) used to treat urinary incontinence?
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alpha adrenergic agonist - increases internal sphincter tone
was associated with strokes in young people (probably from alpha1 peripheral vasoconstriciton raising the BP) |
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What is another drug besides DES and PPA that can be used to treat urinary incontinence?
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Ephedrine and pseudephedrine
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What is urge incontinence?
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A problem with the detrusser muscle of the bladder - muscle gets too contractile and sends messages back to the brain suggesting that there is a need to urinate even though the bladder is not full (overactive bladder syndrome)
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How is Oxybutynin used to treat urge incontinence?
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muscarinic ACh antagonist
reduces bladder contractility |
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Where does acetylcholine act?
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autonomic ganglia
parasympathetic neuroeffector junctions somatic NMJ adrenal medulla CNS |
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Where is a nictonic ACh receptor?
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Sympathetic System: in the synapse between the pre-ganglionic and post-ganglionic neurons; in the synapse between the neuron and the adrenal gland
Parasympathetic system: in the synapse between the pre- and post-ganglionic neurons |
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Where is a muscarinic ACh receptor?
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Parasympathetic system: in the synapse of the post-ganglionic neuron and the effector organ
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What is a cholinergic or cholinomimetic drug?
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A drug that produces ACh-like effects
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What is a parasympathomimetic drug?
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A drug that produces ACh-like effects at the parasympathetic neuroeffector junction
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What is a direct-acting parasympathomimetic drug?
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Agonists at the muscarinic ACh receptor (mAChR agonist)
they act on the muscarinic receptors because they are more peripheral than the nicotinic |
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What is a cholinesterase inhibitor? [a parasympathomimetic drug]
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blockers of the acetylcholinesterases that degrade endogenous ACh
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What is a parasympatholytic drug?
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Drugs that block or inhibits ACh-like effects at parasympathetic neuroeffector junctions
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In general, what are the functions of the sympathetic system?
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increase HR, contracitlity and conduction velocity
dilate bronchioles decrease GI motility, contract sphincter, digestion, etc. |
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In general, what are the effects of the parasympathetic system?
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inhibits the heart (decrease HR, contracitility and conduction velocity)
constrict bronchioles increase GI motility, sphincter relaxation SECRETION! SLUD (salivation, lacrimation, urination, defecation) |
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What are some drugs that are in the Choline Esters family?
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ACh, methacholine, carbachol, bethanechol (urecholine)
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What are some drugs that are cholinomimetic alkaloids (natural products)?
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Pilocarpine (from a Brazilian shrub)
Arecoline (form batel nut in Thailand) Muscarine (from poisonous mushroom) |
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What is Bethanechol (urecholine) used for?
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stimulating GI motility in horses with ileus (it is a very potent constrictor of intestinal muscle - can cause problems with impactions or obstructions)
may cause urination and increased salivation also used for stimulating the urinary bladder for this reason (increases the contraction of the detrusor muscle) it is a muscarinic cholinergic receptor agonist - stimulates contraction of the bladder muscle, muscles of the intestine and stomach, salivation and tear production causes a more frequent need to urinate, diarrhea, appetite loss, vomiting and drooling atropine is an antidote (mAChR blocker) |
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What is Pilocarpine used for?
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treatment of Glaucoma (stimulates tear production)
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What are adverse effects of parasympathomimetic drugs?
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slowing of HR and AV block (cardiac standstill)
increased airway resistance (increased secretions and bronchoconstriction - dyspnea) hypotension SLUD syndrome |
