Pharmacology · single question
Where does epinephrine act in the heart?
Show answer and explanation
Correct answer: C. Beta-1 receptors
- A. Alpha-1 receptors mediate vasoconstriction in skin/mucosa, not the primary cardiac stimulatory effect.
- B. Alpha-2 receptors provide negative feedback on norepinephrine release presynaptically, not the main cardiac action.
- C. Correct. Epinephrine acts on cardiac beta-1 receptors to increase heart rate and contractility (positive chronotropic and inotropic effects).
- D. Beta-2 receptors mediate bronchodilation and vascular smooth muscle dilation (in skeletal muscle vessels), not the primary direct cardiac receptor.
Note: Exam only gives options: A1, A2, B1, B2.