. If we give an injection of acetylcholine to a person, rate of heart beat will a. Increase b. Decrease c. Increases first then decreases d. No effect on heart beat
Option B.Acetylcholine slows the heart rate by activating the M2 muscarinic receptor (M2R) that, in turn, opens the acetylcholine-activated potassium channel (IK,ACh) to slow the firing of the sinus node.
