<prompt> Which of the following antiarrhythmic drugs can decrease the slope of Phase 0 and prolong the action potential duration?LignocainePropanololQuinidineAdenosine  <response>: Na channel blockers reduce the slope of phase 0 whereas K channel blockers prolong the APD. Both of these propeies are present in class Ia antiarrhythmics like quinidine and procainamide. 