Pharmacology Acetylcholine decrease hea rate by which of the following mechanisms? A By decreasing the rate of diastolic depolarization of SA node B By causing delay through AV node C By blocking calcium channels and prolonging the plateau phase D By reducing the rate of ventricular repolarization 💡 Explanation Acetylcholine decrease hea rate by which of the following mechanisms? ✓ Correct Answer: A. By decreasing the rate of diastolic depolarization of SA node