[Analysis of the changes in duration of the action potentials of the myocardial cells of guinea pigs in local anaphylactic reaction and the effect of histamine].

The relationship between the frequency of the spontaneous activity and the action potential duration (APD) has been studied on the right cardiac auricular appendage of guinea pigs during cardiac anaphylaxis (ovalbumine was used as an antigen, 2.10(-4)--2.10(-5 g/ml) and histamine action (1.10(-4)--1.10(-5) g/ml) under the following experimental conditions: a) in normal Tyrode solution; b) under the block of Ca-channels by verapramil (2-4 mg/1) or D-600 (0.2-1 mg/1): c) under the block of K-channels by tetraethylammonium (10-20 mM). Analysis of diagrams interspike interval--APD revealed that the antigen and histamine induced the directi prolongation of the APD usually masked by the positive chronotropic action of these agents. The relative prolongation of APD took place at the whole range of spontaneous frequency. These data supported the hypothesis advanced earlier on the principal role of slow Na-Ca-channels activation in the mechanism of cardiac anaphylaxis and histamine action on the myocardium.