Effect of local anaphylaxis on electrical activity of guinea pig myocardial fibers during inactivation of ?fast? sodium channels

Abstract

A preparation of the right auricle of the guinea pig atrium, preliminarily sensitized to egg albumin, was placed in Tyrode solution containing 20 mM KCl. Because of inactivation of the “fast” sodium channels of the membrane under these conditions stimulation of the preparation evoked only slow low-amplitude responses associated with activation of the “slow” sodium-calcium channels. These responses increased in amplitude and duration when egg albumin (2×10−4 g/ml), histamine (1×10−4 g/ml), and adrenalin (5×10−6 g/ml) were added to the solution. The results confirm the hypothesis of the leading role of “slow” sodium-calcium channels in the mechanism of the changes produced by cardiac anaphylaxis in the electrical activity of the myocardial fibers.