... beactivated)States of Na+-channels during an action potentialSuppression of AP generationProlongation of refractory period =duration of inexcitabilityStimulus25001234Rate of depolarizationK+Antiarrhythmics ... conditions of license.Overview of Modes of Action (A)1. The pumping capacity of the heart isregulated by sympathetic and parasym-pathetic nerves (pp. 84, 105). Drugs ca-pable of interfering ... The plasmalemma also harborsthe sites of action of cardiac glycosides(the Na/K-ATPases, p. 130), of Ca2+an-tagonists (Ca2+channels, p. 122 ), and of agents that block Na+channels (localanesthetics;...