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238 SEcTIoN II Pharmacology ` PHARMACOLOGY—AUTONOMIC dRUGS Pharmacology ` PHARMACOLOGY—AUTONOMIC dRUGS

G-protein–linked second messengers
RECEPTOR G-PROTEIN CLASS MAJOR FUNCTIONS
Adrenergic
q  vascular smooth muscle contraction,  pupillary dilator muscle contraction
α 1
(mydriasis),  intestinal and bladder sphincter muscle contraction

α 2 i  sympathetic (adrenergic) outflow,  insulin release,  lipolysis,  platelet
aggregation,  aqueous humor production
β 1 s  heart rate,  contractility (one heart),  renin release,  lipolysis

β 2 s Vasodilation, bronchodilation (two lungs),  lipolysis,  insulin release,
 glycogenolysis,  uterine tone (tocolysis),  aqueous humor production,
+
 cellular K uptake
s  lipolysis,  thermogenesis in skeletal muscle,  bladder relaxation
β 3
Cholinergic
M 1 q Mediates higher cognitive functions, stimulates enteric nervous system
M 2 i  heart rate and contractility of atria
q  exocrine gland secretions (eg, lacrimal, sweat, salivary, gastric acid),
M 3
 gut peristalsis,  bladder contraction, bronchoconstriction,  pupillary
sphincter muscle contraction (miosis), ciliary muscle contraction
(accommodation),  insulin release, endothelium-mediated vasodilation
Dopamine
s Relaxes renal vascular smooth muscle, activates direct pathway of striatum
D 1
D 2 i Modulates transmitter release, especially in brain, inhibits indirect
pathway of striatum
Histamine
H 1 q  nasal and bronchial mucus production,  vascular permeability,
bronchoconstriction, pruritus, pain

H 2 s  gastric acid secretion
Vasopressin

V 1 q  vascular smooth muscle contraction

V 2 s  H 2 O permeability and reabsorption via upregulating aquaporin-2 in
collecting twobules (tubules) of kidney,  release of vWF

“After qisses (kisses), you get a qiq (kick) out of siq (sick) sqs (super qinky sex).”

H , α , V , Receptor G q Phospholipase C DAG Protein HAVe 1 M&M.
1
1
1
M , M 3 kinase C
1
Lipids PIP 2 +
2+
IP 3 [Ca ] Smooth muscle contraction
in
β , β , β , D , 1 Receptor G s ATP
1
2
3
H , V 2 2+ People who are
2
Adenylate cyclase [Ca ] (heart)
in
G i too (2) MAD
M , α , D 2 Receptor – cAMP Protein kinase A – Myosin light-chain inhibit themselves.
2
2
kinase (smooth
muscle)

FAS1_2019_05-Pharmacology.indd 238 11/7/19 4:08 PM