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Single delayed rectifier channels in frog atrial cells. Effects of beta-adrenergic stimulation

Abstract : The patch-clamp technique with two pipettes was used to record single delayed K+ channels (cell-attached electrode) and to control the potential and the composition of the intracellular compartment (whole-cell electrode). With 30 microM cAMP in the cell and physiological potassium concentrations inside and outside the patch, a channel carrying an outward current was characterized. Its open probability was very low and the channel was recorded in only 5% of patches under control conditions. Increasing intracellular cAMP increased the probability of finding a channel in a patch 10-fold. The channel had the characteristics expected of a delayed rectifier channel. The time-course of its ensemble average resembled the whole-cell current in the same cell. The current-voltage relationship exhibited inward rectification, with a slope conductance of 20 pS in the linear portion and a reversal potential close to EK. Both the open- and the closed-time distributions were described by the sum of two exponentials, suggesting a complicated gating scheme involving two closed states and two open states. The beta-adrenergic stimulation did not change the conductance of the channel, but increased its probability of opening.
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Contributor : Isabelle Duchatelle Connect in order to contact the contributor
Submitted on : Wednesday, December 15, 2021 - 3:43:15 PM
Last modification on : Wednesday, December 15, 2021 - 3:56:05 PM

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I. Duchatelle-Gourdon, H.C. Hartzell. Single delayed rectifier channels in frog atrial cells. Effects of beta-adrenergic stimulation. Biophysical Journal, Biophysical Society, 1990, 57 (4), pp.903-909. ⟨10.1016/S0006-3495(90)82610-2⟩. ⟨hal-03481910⟩



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