Acute actions of testosterone on contractile function of isolated rat ventricular myocytes.

Variation between the sexes in cardiac function have been established. The extent to which sex hormones are responsible for these differences is unclear. The current study was designed to determine whether testosterone acts acutely to enhance contractility of cultured rat ventricular myocytes. Following a 24-h treatment with testosterone (1 microM), isolated rat ventricular myocytes display a 21% increase (P < 0.01) in peak shortening and an 18% decrease (P < 0.02) in time to peak shortening. In accordance with this change, testosterone treatment produced an 18% decline (P < 0.002) in the time to relengthening when compared to vehicle-treated controls. These results provide the first evidence that short-term androgen exposure acts directly to stimulate contractility of isolated rat ventricular myocytes and thus may play a role in regulating cardiac performance in males and thereby contribute to sex differences in cardiac function.