Testosterone modulates cardiomyocyte Ca2 handling and contractile function

Abstract

The extent to which sex differences in cardiac function may be attributed to the direct myocardial influence of testosterone is unclear. In this study the effects of gonadal testosterone withdrawal (GDX) and replacement (GDX+T) in rats, on cardiomyocyte shortening and intracellular Ca2+ handling was investigated (0.5 Hz, 25 °C). At all extracellular [Ca2+] tested (0.5-2.0 mM), the Ca2+ transient amplitude was significantly reduced (by ~ 50 %) in myocytes of GDX rats two weeks postgonadectomy. The time course of Ca+2 transient decay was significantly prolonged in GDX myocytes (tau, 455±80 ms) compared with intact (279±23 ms) and GDX+T (277±19 ms). Maximum shortening of GDX myocytes was marked..