Nonselective beta blockers inhibit which receptors?

• A. Beta-1 only
• B. Beta-2 only
• C. Beta-1 and Beta-2
• D. Alpha receptors

Answer: (C)

Nonselective beta blockers block both beta-1 and beta-2 adrenergic receptors. Blocking beta-1 reduces heart rate and contractility, which helps treat hypertension, angina, and certain arrhythmias, while blocking beta-2 prevents bronchodilation and vasodilation, explaining why these drugs can cause bronchospasm in susceptible individuals. They do not target alpha receptors, which are affected by a different class of drugs. So the receptors inhibited are both beta-1 and beta-2.