Which statement correctly describes the receptor effects of epinephrine?

• A. Alpha-1 increases blood pressure; Beta-1 increases heart rate; Beta-2 bronchodilation.
• B. Alpha-1 increases blood pressure; Beta-1 decreases heart rate; Beta-2 bronchodilation.
• C. Alpha-1 decreases blood pressure; Beta-1 increases heart rate; Beta-2 bronchodilation.
• D. Alpha-1 increases blood pressure; Beta-1 increases heart rate; Beta-2 bronchoconstriction.

Answer: (A)

Epinephrine acts on multiple adrenergic receptors, producing simultaneous effects on the cardiovascular and airway systems. It stimulates alpha-1 receptors on vascular smooth muscle, causing vasoconstriction and increased systemic vascular resistance, which raises blood pressure. It also stimulates beta-1 receptors in the heart, increasing heart rate and contractility. In the lungs, stimulation of beta-2 receptors causes bronchodilation. So the combination of alpha-1 increasing blood pressure, beta-1 increasing heart rate, and beta-2 bronchodilation best reflects epinephrine’s actions. The other patterns don’t fit: beta-1 decreasing heart rate is incorrect, alpha-1 decreasing blood pressure isn’t how epinephrine works, and beta-2 bronchoconstriction is the opposite of what epinephrine does.