Single channel recordings of calcium-activated potassium channels in the apical membrane of rabbit cortical collecting tubules.

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RESUMO

Recordings of single potassium channels from the apical membrane of rabbit cortical collecting tubule have been achieved using the patch-clamp technique. The conductive properties of the channel have been studied in inside-out patches. The slope conductance of the open channel is approximately equal to 90 pS. The channel is selective to potassium over sodium, with a selectivity ratio of 9:1. Decreasing the calcium concentration of the solution bathing the cytoplasmic face of the patch results in a decrease of the open-channel probability. Decreasing the calcium concentration to 10 nM or less completely inhibited channel activity. The channel is also inhibited by barium in a dose-dependent fashion.

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