A patch-clamp study on human sperm Cl- channel reassembled into giant liposome

Aim: To record the single-channel currents and characterize the electrophys iological properties of the Cl- channels in human sperm membrane. Methods: The membrane proteins extracted from the human sperm were reassembled into liposome bilayer, and the liposomes were fused into giant liposomes with a diameter more than 10 mum by dehydrationrehydration procedure. The giant li posomes were used to study the Cl- channel activities by patch-clamp techni que. Results: By patch clamping the giant liposome in an asymmetric NMDG (N -methyl-D-glucamine)-Cl (bath 100// pipette 200 mmol/L) solution system, th ree kinds of single-channel events with unit conductances of (74.1 +/- 8.3) pS,. (117.0 +/- 5.7) pS and (144.7 +/- 4.5.) pS, respectively, were detect ed. Their activities were voltage-dependent and all were blocked by SITS (4 -acetamido-4'-isothiocyanato-stilbene-2', 2'-disulfonic acid) in a concentr ation-dependent manner. By constructing the open and close dwell time distr ibution histograms and then fitting them with exponential function, two tim e constants were obtained in both the open and the close states. The burst activity and conductance substate of the channels were observed. Conclusion : There exist three kinds of Cl- channels with different conductance in hum an sperm membrane at least.