On increasing, vagal tone following occurs in pacemaker: (A) Increased Na+, increased slop, (B) Decreased Na+, decreased slop, (C) Increased Na+, decreased slop, (D) Decreased Na+, increased slop
Answer is B. Na+ influx causes the pacemaker potential (prepotential). Due to vagal stimulation, the Na+ influx decreases, this leads to a decrease in the slop of prepotential.