[Influence of light on membrane potential of Neurospora crassa cells]

In experiments with left atrial and right ventricular tissues fast sodium current (INa) was decreased by substituting sucrose for sodium in Tyrode's solution and with antiarrhythmic drugs--INa blockers (lidocaine, diphenylhydantoine and ethmozine). It was shown that INa decrease results in the growth of refractoriness (R) of the cardiac tissues. The hypothesis is advanced that the R growth caused by INa decrease is one of the mechanisms of selective sensitiveness of ischemic heart tissues to antiarrhythmic drugs--INa blockers.