ANS CV drugs intro Flashcards
for each drug, know: which part of ANS, receptor, effect
3 main fns of parasympathetic system
secretion, SM contraction, inhibit pacemaker cells/CM contraction
3 main fns of sympathetic system
SM contraction, SM relaxation, excite pacemakers and CMs
ACh effect on M2s
NEGATIVE chronotropic and in heart, hyperpolarizes pacemaker cells by opening K+ channels and slowing heart rate (flatten phase 4 slope)
ACh effect on M3
secretion and smooth muscle contraction- pretty much everywhere but heart
NE/EPI effect on a1 (and a2)
SM contraction- vasoconstriction and increased SVR
NE/EPI effect on B1
positive chronotropy and inotropy- increase CO
NE/EPI effect on B2
SM relaxation- vasodilation and lower SVR
major role of a2
presynaptic effect- receptors on presynaptic knob bind NE and promote negative feedback against sympathetic innervation
2 M2 antagonists and fn
atropine and glycopyrrolate- antagonize M2 and raise CO
a1 agonists
midodrine, phenylephrine- vasoconstriction
a1 antagonists
prazosin, tarazosin, doxazosin- vasodilation, lower BP
a2 agonists
clonidine, guanfacine, methyldopa- negative feedback on NE release, less sympathetic stimulation and vasodilation
dobutamine
functions as a selective B1 agonist, has alpha and B2 activity that cancel out (no vascular effects)- increase CO, positive chronotropy and inotropy
Beta antagonists (beta blockers), B1 specific and not
B1: metoprolol, atenolol, acebutol- lower CO
*all the “olol” drugs are beta blockers- some affect B2 as well:
Nadolol, pindolol, propanolol
and B2 and a1: carvedilol and labetolol
notable B2 agonist
albuterol- bronchodilation for asthma
alpha 1 & 2 adrenergic antagonists
phenoxybenzamine, phentolamine, tolazoline- vasodilation and lower BP
EPI receptors and effects
a1, a2, B1, B2- chronotropic/inotropic with vasodilation (B2) at low doses and vasoconstriction (alphas) at high doses
NE receptors and effects
alphas, B1- chronotropic/inotropic, vasoconstriction
major difference b/w NE and EPI
NE has no B2 activity to counteract alpha agonist fn, much greater impact on BP and SVR than EPI
isopreterenol
selective Beta agonist- inotropic and chronotropic B1 affect on CO, B2 activity vasodilates and lowers SVR
dopamine
precursor to NE, selective B1 agonist at low doses, a1 agonist as well at higher doses,
also increases renal perfusion at low doses
organs w/ a1 receptors
eye, vasculature, bladder
organs w/ B2 receptors
salivary glands, lungs, stomach, bladder
organs w/ B1
heart (also only w/ M2)