Na+-permeable channels of human sperm membrane reassembled into giant liposome

Previous data showed that a Na+-transmembrane flux was accompanied with acr osome reaction of sperm. However, the electrophysiological recording and ch aracterization of Na+ current in human sperm membrane have not been yet rep orted. In the present investigation, membrane proteins extracted from human sperms were reassembled into liposome bilayer, and then the liposomes were fused by dehydration-rehydration into giant liposomes with the diameter of more than 10 mum. By patch clamping the giant liposomes two kinds of singl e channel currents were recorded in a NaCl solution system. Both of them we re Na+-carried, TTX-sensitive and strongly rectifying, but with different u nit conductance and open probability. Moreover, bursting activity and chann el-substates as well as two open time constants were observed in the larger channel.