Effects of epinephrine on the Alpha 1 receptor causes:

• A. Increased blood pressure
• B. Increased heart rate
• C. Relaxation of bronchioles
• D. Decreased blood pressure

Answer: (A)

Activating alpha-1 receptors on vascular smooth muscle causes vasoconstriction. When epinephrine binds to these receptors, arterioles constrict, increasing systemic vascular resistance and raising arterial blood pressure. The other effects described come from other receptors: beta-1 stimulation raises heart rate, beta-2 stimulation causes bronchodilation, and decreased blood pressure would come from vasodilation, not alpha-1–mediated constriction. So the alpha-1–driven outcome is an increase in blood pressure.