A Ca-dependent Cl- conductance in cultured mouse spinal neurones.

Long-lasting conductance changes triggered either by brief (millisecond) electrical stimuli and/or entry of calcium ions have been observed in a variety of excitable tissues. The electrical consequences of these events depend on the ion conductance affected and on the ion concentration gradient across the membrane, while the long-lasting nature of the change sustains the cell at either sub- or supra-threshold levels for activation of regenerative action potentials. We report here that many cultured mouse spinal neurones exhibit a voltage-activated chloride conductance that lasts for seconds and is dependent on extracellular calcium, [Ca2+]0. This conductance may repolarize and stabilize the cell at a level subthreshold for generating action potentials, thus complementing the functional roles of Ca-dependent K+ conductances.