Objective: 20-HETE, which is an arachidonic acid metabolite, increases in apoptotic processes and cell loss especially in the cardiovascular system. However, its effects are currently not clarified on cardiac tissue. In order to elucidate its role in the cardiovascular system, it is aimed to examine its effect on cardiomyocyte physiology.

Materials and Methods: In the study, electrophysiological recordings were taken via 20-HETE application on single cardiomyocytes obtained by enzymatic isolation from the left ventricle of the rat heart. Action potentials were measured by current-clamp method. Then Na⁺, K⁺ and Ca²⁺ channel currents were measured with voltage-clamp method. Also, sarcomeric shortening responses were recorded with electrical field stimulation after 20-HETE incubation.

Results: As a result of the 20-HETE application, the shortening amplitude decrease in the normal condition by frequency was disappeared, as well as the function of shortening at the higher frequencies. In addition, it has been determined that 20-HETE significantly reduced the action potential amplitude. This decrease is accompanied by a decrease in voltage-dependent Na⁺ channels current and slow down of their kinetics. Also, the reduction in I_to current density contributes to the decrease in the action potential amplitude. 20-HETE incubation did not have a significant effect on action potential duration and L-type Ca²⁺ channels current.

Conclusion: This study has shown that 20-HETE has important effects on cardiomyocyte excitation-contraction coupling. In particular, it is thought to reduce contraction kinetics by affecting Ca²⁺ sensitivity of the machinery. On the other hand, 20-HETE has important effects on the excitability of the heart.