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:
- Which drugs are used to treat cardiac arrhythmias? (Video 10:09)
- Which drugs are used to treat atrial arrhythmias? (Video 29:56)
- What is the sympathetic nervous system? (Video 22:24)
- Which drugs act on the sympathetic nervous system? (Video 14:05)
- Lecture: Drugs used in Heart Failure
- CAL: G Proteins
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