Abstract
Large conductance channels were observed in the membrane of cultured cardiac cells of newborn rats studied with the patch-clamp technique in cell-attached and inside-out configurations. These channels were observed in ≃4% of the patches. In the cell-attached configuration they exhibited outward rectification and partial inactivation. In the inside-out configuration no rectification occurred but inactivation was present, mainly during hyperpolarizations. Two channels with large single unit conductances (400–450 pS) and one with a smaller conductance (200–250 pS) were frequently observed in the same patch. The two large channels generally had different kinetics. Under steady-state conditions the opening probability of the faster channel appeared to be voltage-independent. The slower channel was activated by depolarization. In asymmetrical solutions the permeability ratios P Na/P Cl were 0.03 and 0.24 for the larger and smaller channels, respectively; corresponding values for P Ba/P Cl were 0.04 and 0.09. It is proposed that in cardiac membranes the chloride permeability system is composed of widely dispersed microclusters forming grouped channels of different types and sizes.
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Coulombe, A., Duclohier, H., Coraboeuf, E. et al. Single chloride-permeable channels of large conductance in cultured cardiac cells of new-born rats. Eur Biophys J 14, 155–162 (1987). https://doi.org/10.1007/BF00253840
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DOI: https://doi.org/10.1007/BF00253840