Modulation by testosterone of an endogenous hERG potassium channel current

hERG (human ether-a-go-go-related gene) potassium (K+) channels are expressed in a range of tissue types including neuroblastoma cells and the heart, in which hERG K+ current is important for action potential repolarization. Whilst gender differences in cardiac repolarization and the QT interval of the cardiac electrocardiogram are well-established, comparatively little is known about regulation of hERG channels by sex hormones. In this study, whole-cell patch-clamp recordings were made at 37 degrees C from SH-SY5Y human neuroblastoma cells to investigate modulation of endogenous hERG K+ channel current (I(hERG)) by testosterone. Acutely applied testosterone at a physiologically relevant concentration (10 nM) produced a modest (approximately 13-15 %) increase in I(hERG) amplitude, whilst a high concentration (1 microM) slightly decreased I(hERG). The stimulatory effect of testosterone was inhibited by the androgen receptor antagonist flutamide (10 microM) and the PI-3 kinase inhibitor wortmannin (1 microM). Chronic (24 h) application of testosterone also augmented IhERG via flutamide-sensitive receptor activation, without modulation of the current's voltage-dependence. These results demonstrate for the first time that testosterone can stimulate (hERG) K+ channels via activation of classical androgen receptors and implicate PI-3 kinase in the acute response.