Sex difference in the repolarization currents of rabbit ventricular cells

Abstract

The current difference between male and female rabbit ventricular myocytes was investigated for elucidating the mechanism of longer QT interval and higher incidence of drug-associated torsade de pointes in female rabbits than in male rabbits. Whole cell patch clamp technique was used to record APD,I_to,I_{k, tail},I_k1 andI_Ca,L of myocytes from left ventricular apex. There was no difference in the membrane capacitance between male and female rabbit myocytes. APD₉₀ was longer in female rabbits (560.4±26.5 ms,n=15) than in male ones (489.0±20.7 ms,n=14),P<0.05. In female rabbit myocytes,I_{K, tail},I_to,I_{Ca, L} were 0.71±0.05 pA/pF (n=17), 8.28±1.03 pA/pF (n=18), 24.5±3.6 pA/pF (n=12) and 9.0±2.3 pA/pF (n=15) respectively. In male rabbit myocytes, they were 0.84±0.07 pA/pF (n=18), 8.60±1.20 pA/pF (n=18), 25.9 ±4.5 pA/pF (n=14) and 9.3±2.6 pA/pF (n=16) respectively.I_{K, tail} in female rabbits was significantly lower than that of male rabbits (P<0.05), but there was no difference inI_to,I_Ki andI_{Ca, I} between male rabbits and female rabbits (P>0.05). The lowerI_{K, tail} of female rabbit myocytes may contribute to the longer repolarization and the higher incidence of drug-associated torsade de pointes.

Keywords

patch clamp technique / ventricular myocytes / potassium current / calcium current / sex difference

References

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