A Calcium-dependent Chloride Channel In Plasma Membrane Of Oocytes From Toad, Bufo Bufo Gargarizans

Objective: To study membrane properties of the fully-grown oocytes from toad, Bufo bufo gargarizans.Method: Two-microelectrode voltage-clamp(TEA)method was used.Results: (1)It was found that a sustained outward current was elicited by membrane depolarization to -30mv or more positive value. Potassium channel blockers(TEA10mmol/L and 4-AP10mmol/L) partly reduced the majority of outward current to 23.4±2.4%.(2)Bath application of Cl—-free Ringer's solution and potassium channel blockers(TEA10mmol/L and 4-AP10mmol/L) could almost completely block the outward current, only remaining 2.2±0.2% .Bath application of chloride channel blocke(rNPPB30μmol/L)and potassium channel blockers(TEA10mmol/L and 4-AP10mmol/L) could almost completely block the outward current, only remaining 2.1±0.2%.Bath application of Ca2+-free Ringer's solution and potassium channel blockers(TEA10mmol/L and 4-AP10mmol/L) could almost completely block the outward current, only remaining 3.2±0.3%.(3) Bath application of calcium channel blockers(Verapamil40μmol/L)and potassium channel blockers(TEA10mmol/L and 4-AP10mmol/L) could almost completely block the outward current, only remain 3.1±0.3%.Conclusion: It was firstly concluded that plasma membrane of Bufo oocyte exist calcium-dependent chloride channel, except potassium channel.