Chlorine anions have a significant influence on the electrophysiological properties of excitable tissues, including myocardium. Chlorine anions and transmembrane chloride currents (ICl) determine the configuration of action potentials (AP) in various regions of hearts. Disruption of transmembrane chloride transport leads to alterations in normal electrical activity, resulting in cardiac pathologies and arrhythmias. Currently, chloride conductivity and expression in the heart and a functional role have been confirmed for several types of macromolecules. These channels include CFTR, ClC-2, CaCC (TMEM16), and VRAC (LRRC8x). Additionally, chloride cotransporters (KCC, NKCC) and chloride-bicarbonate exchangers make a significant contribution to the regulation of intracellular chlorid ion concentration ([Cl-]i) and, consequently, the equilibrium potential for chloride ions (ECl). The review covers the mechanisms by which chloride transmembrane transport influences the bioelectrical activity of cardiomyocytes and the potential functions of chloride and chloride currents in specialized regions of the heart.
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