Verapamil acts by -
Ans. is 'b' i.e., Calcium channel blocker o Calcium channel blockers delay the recovery of `L' type calcium channel from inactivated state to resting state --> depression of pacemaker activity and conduction - negative ionotropic, chronotropic and dromotropic effect. o Amongst CCBs, recovery of Ca' channel is delayed maximally by verapamil and to a lesser extent diltiazem. o DHPs do not delay the recovery - no negative chronotropic, ionotropic or bathantotropic effect, infact sho acting DHPs like nifedipine can cause tachycardia and paradoxically increase the frequency of angina sho acting DHPs should not be used in angina.
Blocking membrane depolarisation
Calcium channel blockers
Membrane stabilising
Blocking membrane repolarisation