title: Calcium channel blockers and early ischemic ventricular arrhythmias: electrophysiological versus anti-ischemic effects.
abstract: Calcium antagonists are able to reduce the incidence of early ischemic arrhythmias when given as pretreatment in a variety of models of acute myocardial regional ischemia. Two possible modes of action are electrophysiologic and anti-ischemic. First, a direct electrophysiologic effect of the calcium antagonist agents on the inward calcium current could inhibit four calcium-dependent phenomena, each of which has been linked to the development of ischemic arrhythmias: the slow response, delayed afterdepolarizations (DADs) and calcium-dependent automaticity, enhanced membrane depolarization and conduction slowing. The special circumstances in which each of these could occur are delineated. An anti-ischemic effect of calcium antagonists must also be considered in some models, because of the negative inotropic, negative chronotropic and coronary and peripheral vasodilator properties. Thus far a specific role for the calcium current in early ischemic arrhythmias has only been shown in a few models and not tested in man.
authors.forename: W A
authors.initials: WA
authors.lastname: Coetzee
authors.forename: S C
authors.initials: SC
authors.lastname: Dennis
authors.forename: L H
authors.initials: LH
authors.lastname: Opie
authors.forename: C A
authors.initials: CA
authors.lastname: Muller
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000188:drug therapy*; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology / Q000627:therapeutic use*; D003327:Coronary Disease / Q000188:drug therapy*; D006352:Heart Ventricles / Q000503:physiopathology; D009206:Myocardium / Q000378:metabolism
chemical_list: D002121:Calcium Channel Blockers; D002118:Calcium