In electrophysiological experiments using the author’s technique for mapping the electrical activity of the myocardium of an isolated heart (Igor V. Kubasov, Andrei Stepanov, Danila Bobkov, Przemysław B. Radwanski, Maxim A. Terpilowski, Maxim Dobretsov and Sandor Gyorke. Sub-cellular Electrical Heterogeneity Revealed by Loose Patch Recording Reflects Differential Localization of Sarcolemmal Ion Channels in Intact Rat // Front Physiol., 2018 https://doi.org/10.3389/fphys.2018.00061), significant changes in the electrogenesis of cardiomyocytes at different stages of myocardial infarction are shown. The described method makes it possible to separately record APs formed by currents of ion channels localized both on the outer plasma membrane (mainly sodium channels of the cardiac type Nav 1.5) and currents of ion-transporting systems localized in the T-system of cardiomyocytes (Na + -channels of the neuronal type Nav 1.6 , LTCC, NCX). Separate registration of these currents can be ensured by appropriate selection of the micropipette tip diameter and the use of selective blockers loaded into the intrapipette solution. In particular, in experiments on the model of hypoxia and AMI, we have shown a significant remodeling of the extracellular-recorded PD of the peri-infarction zone, starting from the early stages of MI and ending with long (up to 6 months) periods (Kubasov, Bobkov, 2018; Kubasov, Vdovkin, Dobretsov, 2018 ).