Sympathetic Nervous System

a1 protein/pathway

Gq protein, IP3-DAG pathway

a1 selective agonist:

phenylephrine

a1 selective antagonist:

prazosin

a1 distribution and effect

• vasoconstriction

• peeing and cumming

• sweating

• gut relaxation

a2 protein, pathway

Gi, AC-cAMP

a2 selective agonist

clonidine

a2 selective antagonist

yohimbine

a2 distribution and effects

• prejunctional nerve terminal - inhibit transmitter release

• brain - decreased sympathetic flow

• pancreatic beta cell - decrease insulin release

• platelets aggregation

• vasoconstriction, only when given locally, IV, or very high oral dose

b1 protein, pathway

Gs, AC-cAMP

b1 selective agonist

dobutamine

b1 selective antagonist

atenolol, metoprolol, bisoprolol

b1 distribution and effects

• SA node - inc rate, chronotropy

• AV node - inc velocity, dromotropy

• Ventricles - inc contractility, inotropy

• kidney (juxtaglomerular cells) - increase renin release

b2 protein, pathway

Gs, AC-cAMP

b2 selective agonist

albuterol

b2 selective antagonist

butoxamine

b2 distribution and effects

• bronchodilation

• vasodilation

• uterus & gut - relaxation

• pancreas - glucagon secretion

• pee

• eye watery

b3 protein, pathway

Gs, AC-cAMP

b3 selective agonist

mirabegron

b3 distribution and effects

• adipose tissue

• detrusor muscle - relaxation