RESUMO
Purpose: We investigated the effects of sex steroids on the maxi-K channel activities of the single smooth muscle cells of the human vas deferens. Materials and Methods: Human vas deferens cells were isolated using proteolytic enzymes (collagense and papain), and then they were employed for an electrophysiological study with using the inside-out patch clamp configurations. The intracellular calcium concentrations were adjusted between 0.1mum to 1mum, and the membrane potentials were depolarized. Results: The maxi-K channels were identified by their single channel conductance and calcium dependency. The application of 10ng/dl estrogen induced a significant increment of the maxi-K channel activities. The effects were not affected by the change of the intracellular calcium concentration. The other sex steroids (progesterone and testosterone) rarely affected the maxi-K channel activities. Conclusions: Estrogen has stimulatory effects on the maxi-K channel activity of human vas deferens. This suggests that estrogen may relax the human vas deferens via maxi-K channel activation.