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pubmed:abstractText |
Cell pairs isolated from adult rat ventricles were used to characterize the electrical properties of the nexal membrane located between the cells. Each cell of a cell pair was connected to a suction pipette so as to enable whole-cell recordings. A double voltage-clamp method was employed which allowed the voltage gradient across the nexal membrane to be controlled. The current-voltage relationship of the nexal membrane was found to be linear over a broad range of transnexal voltages ( +/- 50 mV). The measurements revealed a mean value for the apparent nexal membrane resistance, rn(app), of 3.4 M omega. Taking into account the contribution of an uncompensated series resistance (access resistance), the effective nexal resistance, rn(eff), amounts to 1.7 M omega, approximately. The nexal membrane resistance was found to be insensitive to the sarcolemmal membrane potential, Vm (voltage range tested: -90 mV to +30 mV). The nexal membrane showed no rectifying property, i.e. it allows impulse transmission in both directions equally well. The connexons of the nexal membrane exhibited no time-dependent gating behaviour (time range investigated: 0.1-10 s).
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