Adrenergic (sympathetic)
α1
(Gq protein:
phospholipase C ->
↑IP3, DAG, Ca2+)
α2
(Gi protein: inhibit AC ->
↓ cAMP)
β1
(Gs protein: α
dissociation -> ↑cAMP)
β2
( Gs protein: α
dissociation -> ↑cAMP)
Locations
Effects
Agonists
Antagonists
Vascular SM
GI tract
Penis
Bladder
Eye
GI tract
Penis
Constrict BVs in skin; splanchnics
Constrict sphincter
Ejaculation
Constrict sphincter
Mydriasis (dilates pupil)
↓ motility
Ejaculation
Phenoxybenzamine (noncompetitive, Phc, tachy)
Phentolamine (competitive, Phc, tachycardia)
Prazosin (BPH urinary obstruction, no tachycardia)
Labetalol (more β action at therapeutic dose)
Heart
Kidney
Fat cells
Eye
↑ HR, vent. contractility, AV conduxn, CO
↑ renin ----> ↑Blood Volume -> ↑BP
↑ lipolysis -> ↑ fatty acids -> cardiac m
Dilates ciliary m (far vision)
Norepinephrine (vasoC, inotropic)
Epinephrine (anaphylaxis, cardiac arrest,
asthma)
Dopamine (high dose, vasoC)
Phenylephrine (decongestant, vasoC)
Norepinephrine (see above)
Epinephrine (see above)
Dopamine (see above)
Clondine (a2 in brain -> ↓symp. Outflow,
↓BP. Treat HTN)
Norepinephrine (see above)
Epinephrine (see above)
Dopamine (medium dose)
Isoproterenol (↑SysP,↓DiasP,↓MAP, for
heart block and cardiac arrest)
Dobutamine (inotropic spt in pts with
↓contractility)
Vascular SM (BV’s)
GI tract
Bronchioles
Bladder
Eye
Cholinergic (parasympathetic)
Nicotinic
All CNS ganglia
(Na+, K+, ion channels)
post-G adrenal gland
NMJ of skeletal muscle
Dilate BV in skel. m. (more O2 to mm’s)
↓ motility
Dilate bronchiolar smooth muscle
Relax bladder wall
Dilates ciliary m (far vision)
Epinephrine (see above)
Isoproterenol (see above)
Albuterol (bronchoD, relief of
asthma/exercise bronchospasm)
Terbutaline (anti-bronchospasm; given sc)
Neural signal transduction
Skeletal contraction
Acetylcholine (cause miosis for cataract
surgery; iv bolus -> NO release in
endothelium -> relax arterial smooth
mm’s ->↓BP -> baroreceptor (in healthy
pts) -> ↑HR)
Nicotine (stimulating effect in cortex via
locus ceruleus; reward effect via limbic
system. Used as aid to smoking cessation)
Phenoxybenzamine (noncompetitive, Phc, tachy)
Phentolamine (competitive, Phc, tachycardia)
Yohimbine (rare. ↑Norepi release↓orthostatic
hypotension. Possible aphrodisiac)
Propranolol (HTN, AP, crosses BBB, sedative,
prevent sudden death post MI)
Pindolol (partial agonist = less bradycardia)
Labetalol (HTN, 2nd choice for pregnant women)
Metoprolol (HTN, postMI, AP, CHF, sudden
discontinuation = bad)
Nebivolol (d-iso; l-iso = NO release via β3 on
endothelim)
Bisoprolol (long half-life = 1/day dosing)
Propranolol (see above)
Pindolol (see above)
Labetalol (see above)
Butoxamine (single β2-only selective, not available
for clinical use; experimental only)
Succinylcholine (depolarizing, rapid onset,
fasciculations -> flaccid paralysis)
Trimethaphan, Mecamylamine (ganglionic, used in
HTN emergencies and aortic aneurysm)
Botox (kills SNARE in pre-S nerve, no ACh release)
Tubocurarine (non-depolarizing, competes w/ACH
@ NMJ, use w/ neostigmine to ↑ACh)
“Tubucurarine analogs:” Pancuronium,
Rocuronium, Vencuronium
Muscarinic
Post-G, on effector organs ↓HR, ↓atrial contractility, ↓AV node
Acetylcholine (see above)
Succinylcholine (See above)
(Heart: Gi protein, open
conduction.
Pilocarpine (for dry mouth, crosses BBB)
Atropine (pre-anasthetic, 'shroom posion;
K+ channel -> ↓HR)
↑ GI motility
Bethanechol (for postop urinary retention organophosphate AChE Inhib antidote)
(Smooth m, glands: Gq
Constrict: bronchiolar smooth m, pupil
and to ↑ GI motility)
Scopolamine (CNS effects, cross BBB, Parkinson’s
protein: phospholipase
(miosis), ciliary m, urinary bladder
Muscarine (‘shroom poison. HA, N/V,
tremor, motion sickness)
C -> ↑IP3, DAG, Ca2+)
Relaxes: bladder & GI sphincters
pharyngeal constriction,
Ipratropium bromide (quaternary atropine
Penile erection
bronchoconstriction, dyspnea, death)
derivative, inhaled, asthma, COPD)
Glycopyrrolate (quaternary atropine derivative,
pre-op to ↓ secretions, post-op to reverse skel. m
relaxant effect)

BV = Blood Vessel. mm’s = muscles. VasoD = vasodilation, VasoC = vasoconstricton. Phc = pheochromocytoma. AP = angina pectoris.

Effects and locations are respective (aligned) for adrenergics, not for cholinergics. Drugs that hit up more than one receptor are listed first.

Adrenal medulla is weird. Nicotinic synapse on the medulla, then it releases norepi/epi (80/20) for fight or flight response.

Sweat glands are also weird. Eccrine = symp control, muscarinic r’s. Apocroine = symp control, a1 r’s.

Dopamine in low doses= D1 r’s in kidney smooth muscle bed  vasodilation.

Epi = no effect on BP. Norepi = strong ↑BP -> (in healthy pts) baroreceptor reflex -> ↓HR. ACh = ↓in BP -> baroreceptor (in healthy pts) -> ↑HR