A. Electrophysiological basis of arrhythmias 2. Slow and fast response cells Slow response cells: pacemaker cells fast response cells: conduction and contraction cells Fast response Slow response phase 4 potential -90 mV 70 mV depolarization Na, 120 mV, 1-2 ms Ca+, 70 mV, 7 ms automaticity low( 0.02 V/s) high( 0.1 V/s) conduction fast( 200-1000 V/s) slow( 10 V/s) effects conduction pacemaker◼ 2. Slow and fast response cells ◼ Slow response cells：pacemaker cells ◼ fast response cells：conduction and contraction cells Fast response Slow response phase 4 potential －90 mV －70 mV depolarization Na+ , 120 mV, 1-2 ms Ca2+, 70 mV, 7 ms automaticity low（0.02 V/s） high（0.1 V/s） conduction fast（200-1000 V/s） slow（10 V/s） effects conduction pacemaker A. Electrophysiological basis of arrhythmias