Vasoactive compounds

Question 1

Antihypertensive drugs act at

Answer 1

Sympathetic nervous system, RAAS or endothelium-derived mediators.

Question 2

Indirectly acting vasodilators

Answer 2

• Drugs that interfere with the sympathetic nervous sytem (e.g. alfa1-adrenergic receptor antagonists).
• Drugs that block the RAAS (renin inhibitors, ACE inhibitors, AT1 receptor antagonists).
• Drugs or mediators that stimulate endothelial NO release (e.g. acetylcholine, bradykinin).
• Drugs that block the endothelin: endothelia synthesis, or endothelia receptor antagonists.

Question 3

Ca channel antagonists - Nifedine

Answer 3

MOA:
L-type calcium channels are voltage-gated channels responsible for allowing entry of Ca2+ into cells in response to membrane depolarization. Calcium channel antagonists block L-type calcium channels, preventing influx of calcium ions to cells. In vascular smooth muscle cells, calcium influx through L-type calcium channels is essential for muscle contraction. By blocking calcium entry into vascular smooth muscle cells, calcium channel antagonists cause relaxation of the smooth muscle, leading to vasodilation.

Indication: treat hypertension, angina, arrhythmia.

Side-effects: swelling.

Question 4

K cannel openers - pinacidil

Answer 4

MOA: Bind and activate specific types of potassium channels. This binding induces a conformational change in the channel protein, leading to channel opening and allowing potassium ions flow out of the cell. This leads to hyperpolarizing, which leads to relaxation of smooth muscle cells and vasodilation.

Indication: in severe hypertension unresponsive to other drugs.

Side-effects: male pattern hair growth, salt and water retention, reflex tachycardia.