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76 Cards in this Set
- Front
- Back
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What is norepinephrine's precursor?
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Dopamine
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What is norepinephrine metabolized by?
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Monoamine Oxidase (MAO)
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Vesicles are how norepinephrine is stored at terminal bouton. What agent blocks aggregation of norepinephrine into vesicles?
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Reserpine
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What agents block the release of NE into the synaptic cleft?
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Guanethidine, bretylium
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By what mechanism at the level of neuron does cocaine achieve it's effects?
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Cocaine (among other agents) blocks norepinephrine reuptake at the synaptic cleft.
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Which adrenergic receptor can be stimulated to block further release of NE?
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Alpha-2
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What do alpha-1 receptor second messengers effect?
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Activate phospholipase C, increase IP3 and intracellular Ca
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What do alpha-2 receptor second messengers effect?
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Inhibit adenylyl cyclase and decrease cAMP.
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What do beta-1/2 receptor second messengers accomplish in myocardial cells?
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Stimulate adenylyl cyclase and increase cAMP
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How reactive are adrenergic receptors to epinephrine vs. norepinephrine?
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Epinephrine causes a greater reaction in alpha-1,2, and especially beta-2 receptors.
There is no difference in reactivity for beta-1 receptors. |
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What are the effects of beta-1 (and some 2) stimulation on the heart at the level of nodes, HIS bundle and myocardium?
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SA node: increase HR
AV node: increase conduction speed HIS: increase conduction speed AND automaticity Myocard: increase contractility |
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What are the effects of beta-1 stimulation on the kidneys?
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Increase renin secretion, which activates angiotensin and aldosterone, constricting vessels and increasing reabsorption of water.
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What are the effects of beta-2 stimulation on smooth muscle?
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Relaxation (countered in arterioles by alpha-1 and angiotensin), including ciliary muscles, enabling distance vision.
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What are the effects of beta-2 stimulation on skeletal muscle?
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Increase K uptake
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What are the metabolic effects of beta-2 stimulation?
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Increase glycogenolysis and insulin secretion.
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What are the effects of alpha-1 stimulation on smooth muscle (not intestine)?
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Contraction (helped by angiotensin, countered by beta-2).
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What are the effects of alpha-1 stimulation on intestine?
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Relaxation! Remember that cholinergic (parasympathetic) system is for resting and digesting. Sympathetic stimulation will let sleeping guts lie.
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What are the effects of alpha-1 stimulation on the eye?
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Radial muscle contracts
Lacrimal glands secrete tears. |
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What are the metabolic effects of alpha-1 stimulation?
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Increase glycogenolysis.
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What are the effects of alpha-1 stimulation on the kidney?
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Decrease renin secretion (counteract beta-1 stimulation)
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What are the effects of alpha-2 stimulation? There were only 2 stated.
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Pancreas: Decrease insulin secretion (counteract beta-2 stimulation) and decrease release of NE.
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Which of the following does NOT result from stimulation of beta receptors by epinephrine?
Bronchodilation Increased HR Increased glycogenolysis Arteriolar vasoconstriction Intestinal muscle relaxation |
Arteriolar vasoconstriction - this is achieved by alpha-1 stimulation.
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If you were to design a drug for pheochromocytoma, what would be it's mechanism of action?
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alpha, then beta blockade (beta blockers would result in unopposed alpha stimulation, causing possibly lethal hypertension due to vasoconstriction)
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From what enzyme and precursors are ACh synthesized?
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Choline acetyltransferase, using choline and acetyl coA
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What agent reduces choline uptake into postganglionic ACh producing cells?
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Hemicholinium
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What agent inhibits ACh storage in vesicles?
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Vesamicol
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What agent inhibits ACh's release at the synaptic cleft?
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Botulinum toxin
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How is ACh removed from the syaptic cleft?
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AChE - removes, but reuptake is minimal
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Which receptors (nicotinic vs. muscarinic) are quicker to respond?
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nicotinic
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What are the effects of muscarinic receptors via 2nd messengers?
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M1,3,5 - increase intracellular Ca and protein phosphorylation
M2,4 - increase K permeability and decrease cAMP (just like alpha-2) |
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Where are M2 receptors located?
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SA and AV nodes, atria and ventricles
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What are the effects of M2 stimulation?
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SLOWS CONDUCTION via: Increased potassium permeability (inhibitory effect)
Decreases adenylyl cyclase activity (less cAMP) Decreased Ca permeability |
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Where are M3 receptors located?
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Smooth muscle: sphincters, vessels, glands
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What are the effects of M3 stimulation
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Relaxation of blood vessels (when endothelium intact) via endothelial NO release. Relaxation of sphincters, increased gland secretions
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What are the effects of muscarinic stimulation on the heart and vascular smooth muscle?
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SA: Lower heart rate
AV: slowed conduction Myocardium: Lower contractility Vasc smooth muscle: relaxation |
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What cranial nerve is responsible for cardiac muscarinic stimulation?
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CN X: Vagus
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What are the effects of muscarinic stimulation outside of the heart/vascular system?
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Contraction of GI/bronchiolar, eye muscles;
Relaxation of urinary/GI sphincters; Increased gland production |
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What are the effects of epinephrine?
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HEART beta-1: increased chronotropic (SA), dromotropic (AV), and inotropic (contractility) effects
VASC: alpha-1 increases @ high doses, beta-2 decreases at low doses BRONCH: beta-2 dilates |
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What are the effects of norepinephrine?
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alpha-1, beta-1 agonist.
SIGNIFICANT bp and contractility (inotropy) increase, because no beta-2 vasodilation like with epinephrine. |
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What would you expect to see if you administered epinephrine IV into an elderly patient for heart failure, and due to his brittle veins, noticed that some of the IV fluid had leaked into the surrounding tissue?
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Significant necrosis can be expected from any alpha-1 agonist if it extravasates from IV administration
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What is the precursor of norepinephrine?
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dopamine
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Which adrenergic receptors does dopamine stimulate?
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alpha-1, beta-1;
Also stimulates d-1 receptors, dilating mesenteric, renal and coronary vasculature |
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What are the dose-dependent effects of dopamine?
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Low (1-2mcg/kg/min): renal/mesenteric vasodilation
Medium (5-10 mcg/kg/min): increased chronotropy, inotropy (HR, contractility) High (10-20 mcg/kg/min): inc vasoconstriction, chronotropy, inotropy |
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What drug can you administer in low doses to improve renal function?
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dopamine
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What drug (from the list) is used in cardiogenic shock to increase inotropy rather than peripheral resistance?
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dobutamine (also isoproterenol, but more likely to cause reflex tach)
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What drug (from the list) used as a nasal decongestant can cause significant alpha-1 stimulation, raising blood pressure and risk of stroke?
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pseudoephedrine (also ephedrine and phenylpropanolamine, but both FDA banned)
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What beta-2 agonist is used in rescue inhalers for asthma?
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albuterol
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What results from beta-1 overstimulation?
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Tachycardia, increased myocardial O2 demand, arrhythmia, cardiac damage
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What is a risk of intermittant beta-1 agonist infusion for decompensated heart failure?
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Increased overall mortality
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What results from beta-2 (respiratory) overstimulation?
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skeletal muscle tremors, tachycardia, arrhythmias, hypokalemia
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What results from alpha-1 overstimulation?
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severe BP elevation, increasing myocardial O2 demand, predisposing to stroke and cardiac damage
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What are alpha blockers used for?
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HBP (relaxes vascular smooth muscle), BPH (improves urinary flow)
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What is a side effect of alpha-1 blockade?
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Orthostatic hypotension or syncope with first or increase in doses
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What alpha blockers are used for blood pressure control?
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block a-1 =SIN
prazosin, terazosin, doxazosin |
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What alpha blocker is used for BPH to improve urine flow>
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tamsulosin - blocks a-1a subtype, specific to prostate
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What would a combined alpha-1/2 blockade (ex: phentolamine) be useful in treating?
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pheochromocytoma
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What are adverse events from combined alpha-1/2 blockade (e.g., phentolamine)?
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severe hypotension causing reflex tachycardia, arrhythmias and myocardial ischemia
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How can you achieve selective beta-blockade (without blocking other adrenergic receptors)?
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It's dose dependent: higher doses mean lost selectivity
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What intrinsic property of some beta-blockers is less useful in treating ischemic heart disease?
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intrinsic sympathomimetic activity that occurs with low sympathetic tone (agonism as well as blockade)
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What are beta blockers used for?
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Everything!
HBP, Ischemic heart disease, systolic heart failure, arrhythmias Also Glaucoma, Thyroid storm, stage fright and migraine prevention |
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What are adverse effects of beta blocker use?
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Decompensated systolic heart failure, AV block, sinus bradycardia, bronchoconstriction, lowered HDL, difficult to identify hypoglycemia in DM, peripheral vasoconstriction, nightmares and sedation
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How do parasympathomimetics work?
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Stimulate muscarinic receptors (direct) , OR inhibig AChE (indirect)
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What are the representative beta blockers we need to know for this exam?
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beta blockers = LOL
Atenolol Metoprolol Propanolol Pindolol Carvedilol Labetalol |
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What class are the following medications?
Bethanechol Methacholine Pilocarpine |
Direct-acting muscarinic agonists (parasympathomimetics)
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What is pilocarpine indicated for?
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Xerostomia (permanent dry mouth) and glaucoma
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What is bethanechol used for?
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gastroparesis and urinary retention in patients without obstruction
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In what class are the following?
Edrophonium Physostigimine Pyridostigmine Organophosphate pesticides Donepezil |
Indirect-acting muscarinic agonists (parasympathomimetics), which act to block AChE
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What are indirect-acting parasympathetic agonists used for?
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Myasthenia gravis (-stigmines, to increase AChE at NMJ)
Alzheimers (Donepezil) Counteract nerve gas or antimuscarinic poisoning Other conditions benefited by direct-acting agents (glaucoma, xerostomia, gastroparesis) |
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Adverse effects of muscarinic agonists
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Bradycardia, hypotension, bronchoconstriction, GI distress and increased acid secretion
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What agent can you prescribe for organophosphate (muscarinic agonist) poisoning?
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pralidoxime (2-PAM) reactivates cholinesterase
*Also respiratory support |
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What are the effects of antimuscarinic drugs?
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Cause the following:
Increased HR, conduction velocity through AV node, block of reflex bradycardia, bronchodilation, reduced lung secretions, inhibit GI/GU tone, dilated pupils, cycloplegia, lowered sweat and dry mouth |
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What antimuscarinic drug is used for significant bradycardia?
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atropine
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What antimuscarinic drug is used for motion sickness?
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Scopolamine
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What antimuscarinic drugs are useful in Parkinson's because they improve the effects of relative cholinergic excess?
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Benztropine and trihexylphenidyl
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What effect does oxybutynin (Ditropan) have on the urinary tract?
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Antispasmodic for overactive bladder.
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What condition is ipratropium used to treat?
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COPD - administered via aerosol, does not cross BBB and has low systemic absorption
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