Calcium-activated potassium channels recorded from rat neocortical neurons in cell culture.
Rat neocortical neurons in cell culture were studied with the patch-clamp technique in order to determine the properties of a large-conductance K+ channel in excised inside-out patches. In the presence of a physiological ionic gradient for K+ across the patch membrane ([K+]i = 120 mM; [K+]o = 3 mM), outward channel activity was detected when the patches were brought to membrane potential values less negative than -30 mV. Depolarization of the membrane increased the magnitude of the current. The I-V relationship displayed rectification at negative membrane potentials. When the I-V curve was differentiated the slope conductance calculated at 0 mV membrane potential was 120 pS. The single-channel permeability was 5.2 x 10(-13) cm/s and the current flow through the open K+ channel could be modeled using the constant-field electrodiffusion theory. K+ channel opening was not observed following removal of Ca2+ from the intracellular surface of the membrane. Our experiments indicate that, as in other cell types, rat neocortical neurons in culture exhibit a large-conductance K+ channel which is activated by Ca2+ acting on the cytoplasmic surface.
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Dipartimento di Medicina Sperimentale e Scienze Biochimiche, Università di Roma Tor Vergata, Rome, Italy.
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D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000502:physiology*; D004594:Electrophysiology; D008564:Membrane Potentials; D009474:Neurons / Q000502:physiology*; D010539:Permeability; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains
D015221:Potassium Channels; D011188:Potassium; D002118:Calcium