Which statement best describes the effect of beta-adrenergic blockers?

Which statement best describes the effect of beta-adrenergic blockers?

• A. They increase cardiac output and heart rate
• B. They reduce cardiac output, heart rate and force
• C. They increase renin release
• D. They have no effect on blood pressure

Answer: (B)

Blocking beta-adrenergic receptors blunts the heart’s response to sympathetic stimulation, reducing heart rate and the strength of its contractions. This negative chronotropy and negative inotropy lowers cardiac output. Beta receptors on kidney juxtaglomerular cells also drive renin release; blocking them decreases renin, which helps lower blood pressure. So the best description is that beta-adrenergic blockers reduce cardiac output, heart rate, and contractile force (and also reduce renin release), rather than increasing these parameters or having no effect on blood pressure.

Blocking beta-adrenergic receptors blunts the heart’s response to sympathetic stimulation, reducing heart rate and the strength of its contractions. This negative chronotropy and negative inotropy lowers cardiac output. Beta receptors on kidney juxtaglomerular cells also drive renin release; blocking them decreases renin, which helps lower blood pressure. So the best description is that beta-adrenergic blockers reduce cardiac output, heart rate, and contractile force (and also reduce renin release), rather than increasing these parameters or having no effect on blood pressure.