Ion-channels in human sperm membrane and contraceptive mechanisms of male antifertility compounds derived from Chinese traditional medicine.
Ion channel plays a key role in maturation, capacitation and acrosome reaction of sperm. However, as it is difficult to record channel currents from a mature mammal sperm directly by patch-clamp technique, there were no basic data on the types and properties of the channels in human sperm until the method reconstituting the channels into bilayer was used. By reconstituting the channel proteins isolated from sperm membrane into phospholipid-forming bilayer, we have characterized several kinds of Ca2+-, Na+-, K+-, and Cl--permeable channels with different conductance and properties in human sperm membrane. To study the channels in spermatogenic cells is another approach to understand the ion-channels in mature sperm. The cell is used as a model to analyze the effects of male antifertility agents on Ca2+-channel. To date, several male contraceptives derived from Chinese traditional medicine have been attached worldwide interest, a lot of compounds have been purified from them, and the antifertility effects of some compounds were demonstrated. We studied the effects of gossypol and several compounds isolated from Tripterygium wilffordii on Ca2+ channel in mouse spermatogenic cells and found that each of them inhibited the channel and sperm acrosome reaction at a proximate concentration, suggesting that the inhibition of Ca2+ channels may be one mechanism of the antifertility effects of these contraceptives.Keywords: