Which statement best describes the primary effect of beta blockers?

• A. Lower blood pressure
• B. Increase heart rate
• C. Decrease urine output
• D. Bronchodilation

Answer: (A)

Beta blockers work by blocking beta-adrenergic receptors, mainly in the heart and kidneys, which blunts sympathetic stimulation. In the heart this slows the heart rate and reduces the force of contraction, lowering cardiac output. In the kidneys they decrease renin release, which lowers the renin–angiotensin–aldosterone system activity and helps reduce vascular resistance and volume. The combined effect is a drop in arterial blood pressure, which is the primary outcome these drugs achieve. The other statements don’t describe the main action: beta blockers do not increase heart rate (they decrease it), they do not create bronchodilation (and nonselective ones can even cause bronchoconstriction in susceptible individuals), and urine output is not the central effect even though renin suppression can influence fluid balance.