On increasing vagal tone following occurs in pacemaker: (A) Increased K+ increased slop, (B) Decreased K+ decreased slop, (C) Increased K+ decreased slop, (D) Decreased K+ increased slop
Answer is B. When the cholinergic vagal fibers to nodal tissue are stimulated, the membrane becomes hyperpolarizedThe slope of the prepotentials is decreased because the acetylcholine released at the nerve endings increases the K+ conductance of nodal tissue.Which cause rapid efflux of K+Ref: Ganong's Review of Medical Physiology Twenty-Third Edition Page No: 491