Aim: To record the single-channel currents and characterize the electrophysiological properties of the C1^- 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 10μm by dehydrationrehydration procedure. The giant liposomes were used to study the C1^- channel activities by patch-clamp technique. Results: By patch clamping the giant liposome in an asymmetric NMDG (N-methyl-D-glucamine)-C1 (bath 100//pipette 200 mmol/L) solution system, three 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 detected. Their activities were voltage-dependent and all were blocked by SITS (4-acetamido-4′-isothiocyanato-stilbene-2′, 2′-disulfonic acid) in a concentration-dependent manner. By constructing the open and close dwell time distribution histograms and then fitting them with exponential function, two time 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 C1^- channels with different conductance in human sperm membrane at least.
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