Physiology Acetyl choline decreases heart rate by: A Acting on specific K+ channels and increasing efflux B Acting on Ca2+ channels and increasing efflux C Acting on specific K+ channels and increasing influx D Acting on specific Ca2+ channels and increasing influx 💡 Explanation Acetyl choline decreases heart rate by: ✓ Correct Answer: A. Acting on specific K+ channels and increasing efflux