Mechanism of action of epinephrine in cardiopulmonary resuscitation is -

Ans. is 'b i.e., Increase S.A. node activity "Epinephrine speeds the hea by accelerating the slow depolarization of SA nodal cells that takes place during diastole, i.e., during phase 4 of the action potential. Consequently, the transmembrane potential of the pacemaker cells rises more rapidly to the threshold level of action potential initiation. The amplitude the action potential and the maximal rate of depolarization (phase 0) also are increased."