UNDER REVIEW (April 2017)

Mechanism of Action:

Beta-1 and beta-2 adrenoreceptor agonist, alpha adrenoceptor agonist. Beta and alpha adrenoceptors are 7TM G-protein coupled receptors (GPCRs). Occupation of cardiac beta1 adrenoreceptors (by the endogenous ligand, noradrenaline, released from sympathetic [(nor)adrenergic] nerve endings; or by the circulating hormones adrenaline and noradrenaline, reflexly released into blood by the adrenal medulla; or by injected adrenaline) acts via G-protein-coupled activation of adenylate cyclase, which increases cAMP, leading to activation of protein kinase A (PKA). In the heart PKA phosphorylates Ca2+ channels, increasing inward Ca2+ current and hence force of contraction. Also get increased heart rate and electrical excitability. Adrenaline is also an aplha-adrenoceptor agonist, causing vasocontriction and a rise in mean BP via constriction of resitance vessels (arterioles).

Lecture and CAL material: