Atenolol and metoprolol specifically act on which type of beta receptor?

• A. Beta-2
• B. Nonselective
• C. Beta-1
• D. Alpha-1

Answer: (C)

Atenolol and metoprolol are both beta-blockers that are primarily selective for beta-1 receptors. These receptors are predominantly found in the heart, where their activation increases heart rate and contractility. By specifically targeting beta-1 receptors, atenolol and metoprolol effectively reduce heart rate and myocardial contractility, which is beneficial in managing conditions such as hypertension, heart failure, and arrhythmias.

The selectivity of these drugs for beta-1 rather than beta-2 receptors is key to their therapeutic effects while minimizing certain side effects associated with non-selective beta-blockers, which can affect both beta-1 and beta-2 receptors. This selectivity helps to avoid bronchoconstriction that may occur with beta-2 blockade, particularly in patients with respiratory issues like asthma.

In summary, the correct answer highlights the specific action of atenolol and metoprolol on beta-1 receptors, which is essential for understanding their pharmacological effects and appropriate clinical use.