Which statement about calcium channel blockers is true?

Which statement about calcium channel blockers is true?

• A. They inhibit calcium entry into vascular smooth muscle and cardiac myocytes
• B. They block beta adrenergic receptors
• C. They increase aldosterone release
• D. They increase renin secretion

Answer: (D)

Calcium channel blockers work by blocking L-type calcium channels, which reduces calcium entry into vascular smooth muscle and, for some agents, into cardiac myocytes. This causes vasodilation and can lower blood pressure, with some agents also slowing the heart. A key secondary effect occurs in the kidney. Calcium influx into juxtaglomerular cells normally helps keep renin release in check. When calcium entry is blocked, this inhibitory signal is removed, so renin secretion increases. This RAAS-driven response helps explain why these drugs can raise renin levels despite their vasodilatory effects. So, the statement that calcium channel blockers increase renin secretion reflects this renal mechanism, making it true. They do not act by blocking beta receptors, and their direct effect on aldosterone is indirect through renin/angiotensin changes rather than a primary action to increase aldosterone itself.

Calcium channel blockers work by blocking L-type calcium channels, which reduces calcium entry into vascular smooth muscle and, for some agents, into cardiac myocytes. This causes vasodilation and can lower blood pressure, with some agents also slowing the heart.

A key secondary effect occurs in the kidney. Calcium influx into juxtaglomerular cells normally helps keep renin release in check. When calcium entry is blocked, this inhibitory signal is removed, so renin secretion increases. This RAAS-driven response helps explain why these drugs can raise renin levels despite their vasodilatory effects.

So, the statement that calcium channel blockers increase renin secretion reflects this renal mechanism, making it true. They do not act by blocking beta receptors, and their direct effect on aldosterone is indirect through renin/angiotensin changes rather than a primary action to increase aldosterone itself.