This review focuses on the fast testosterone actions on the cell membrane principally on the Sertoli cells, its predominant effect, i.e. an increase in [Ca2+]i and the possibility of its actions being mediated by KIR (ATP) channels. The regulation of the K+ ATP channels by phosphatidylinositol-4,5-bisphosphate depletion on the cell membrane as a result of the action of testosterone, its putative receptors, and the phospholipase C - phosphatidylinositol-4,5-bisphosphate pathway are discussed. The electrostatic interaction between anionic and cationic charges on the K+ ATP modulation is also considered, in the light of testosterones effect on phospholipase C - phosphatidylinositol-4,5-bisphosphate hydrolysis. Thus, the interaction of testosterone with its putative receptors, phospholipase C, phosphatidylinositol-4,5-bisphosphate, and K+ ATP channels (or other KIR channels) in the membrane may be one of the mechanism of rapid testosterones physiological action on some classes of cells.