activation of a1 receptors leads to what
activation of muscle contraction
- SM = vasoconstriction
- cardiac m = increased contractile force on heart
exception of a1 normal effect location
in the gut
- causes relaxation due to hyperpolarization of Ca2+/K+ channel
- K+ out
activation of a2 receptors leads to what
vascular smooth muscle contraction
decreased insulin secretion
decreased release of NE (presynaptic a2 receptors)
potency in order of agonists in a-receptors
epi>norep»isoproterenol
what are a1 receptors preferentially activated by
phenylephrine
what are a2 receptors preferentially activated by?
clonidine
activation of the B receptors leads to what
activation of adenylyl cyclase and increased concentrations of cAMP through Gs proteins
B1 receptors are mainly found in ___
-activation leads to what
myocardium
-activation = increased force and rate of heart contraction and AV nodal conduction velocity
B2 receptors are found on _____ and most other sites
-activation leads to what
smooth muscle
-activation causes vascular, bronchial, genitourinary, and GI SM to relax
B1 receptors preferentially respond to agonist ____
dobutamine
B2 receptors preferentially respond to the agonist ___
terbutaline
B3 receptors are found only in ___ and activation leads to
adipose tissue
-activation = lipolysis
reactivity of B1 to norep and ep
Epi = NE
reactivity of B2 to norep and ep
Epi»NE
reactivity of norep and ep to B3
NE >Epi
