Effects of Non-Opiate Analogue of Leu-Enkephalin on the Ion Currents, Number of Nucleoli, and p53 Expression in Isolated Cardiomyocytes of Albino Rats.

Acute exposure of isolated ventricular cardiomyocytes to non-opiate analogue of leu-enkephalin (NALE peptide: Phe-D-Ala-Gly-Phe-Leu-Arg) in a concentration of 100 μg/liter and 6-h incubation in NALE solution did not significantly change ATP-dependent K⁺ current, L-type Ca²⁺ current, p53 protein expression, and number of nucleoli in the cardiomyocyte nuclei. Incubation of cardiomyocytes with NALE (100 μg/liter) in combination with NOP receptor blocker J-113397 (1 mg/liter) was followed by an increase in Ca²⁺ L-type current and the number of p53⁺ cells. The exposure of cardiomyocytes to NALE in a concentration 1000 μg/liter induced similar changes in the studied parameters (increase in Ca²⁺ L-type current and number of p53⁺ cardiomyocytes); an increase in the mean number of nucleoli was also observed. Our findings suggest that NALE peptide has direct effect on cardiomyocytes and NOP receptors are involved in this effect.