Adrenergic receptors

Question 1

Alpha-1 receptors

Answer 1

Are on vascular smooth muscle, mediated vasoconstriction

Gq coupled, PLC, IP3 and DAG, Ca++

NE > E

Question 2

Alpha-2 receptors

Answer 2

The Presynaptic Adrenergic autoreceptor

Gi/Go coupled, hyperpolarizing presynaptic channel, opens K+ channels and inhibits Ca++ channels

Question 3

Beta-1 receptors

Answer 3

Cardiac myocyte adrenergic receptors

Gs coupled

Inotropic, via PKA activation, and its phosphorylation of:

L-type VDCCs, increases their activity

Phospholamban, PKA inhibits phospholamban, disinhibiting a Sarcoplasmic Ca++ pump, and thereby increasing the sarcoplasmic Ca++ concentration, causing greater Ca++ release on activation and more powerful contraction.

E==NE

Question 4

Mechanism of cardiac glycosides action

Answer 4

INHIBITS the Na/K pump,
Increases intracellular Na+
Decreases activity of the Na+/Ca++ exchanger, causing less Ca++ to be pumped out of the cell.
Increasing Ca++ intracellularly as well.

Question 5

Beta-2 receptors

Answer 5

On very FEW, specific vascular smooth muscle populations

Coronary vessels,
some skeletal vessels

Gs coupled,

elevates cAMP, PKA activates mysoin phosphorylase, relaxation

is the ONLY adrenergic receptor that is more sensitive to epinephrine
Epinephrine» NE

Question 6

Beta-3 receptors

Answer 6

on adipose

Gs

Ne>E