Which is a Beta-1 receptor effect on the heart?

Which is a Beta-1 receptor effect on the heart?

• A. Increase force of contraction
• B. Bronchodilation
• C. Decrease conduction
• D. Vasodilation

Answer: (A)

Activation of Beta-1 receptors in the heart increases how strongly the heart muscle contracts. This positive inotropic effect happens because Beta-1 stimulation raises calcium availability in cardiac cells, via the cAMP-PKA pathway, so each beat generates more force. That’s why the best choice is the increase in force of contraction. Bronchodilation is mainly a Beta-2 receptor effect on airway smooth muscle, not a Beta-1 heart effect. Decrease in conduction would contradict Beta-1 activity, which actually speeds up electrical conduction in the heart. Vasodilation is largely driven by Beta-2 receptors in vascular smooth muscle, rather than Beta-1.

Activation of Beta-1 receptors in the heart increases how strongly the heart muscle contracts. This positive inotropic effect happens because Beta-1 stimulation raises calcium availability in cardiac cells, via the cAMP-PKA pathway, so each beat generates more force. That’s why the best choice is the increase in force of contraction.

Bronchodilation is mainly a Beta-2 receptor effect on airway smooth muscle, not a Beta-1 heart effect. Decrease in conduction would contradict Beta-1 activity, which actually speeds up electrical conduction in the heart. Vasodilation is largely driven by Beta-2 receptors in vascular smooth muscle, rather than Beta-1.