A stretch-activated K+ channel in the basolateral membrane ofXenopus kidney proximal tubule cells |
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Authors: | Katsumasa Kawahara |
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Institution: | (1) Department of Physiology, Faculty of Medicine, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, 113 Tokyo, Japan |
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Abstract: | The present study examined whether a basolateral potassium ion (K+) channel is activated by membrane-stretching in the cell-attached patch. A K+ channel of conductance of 27.5 pS was most commonly observed in the basolateral membrane ofXenopus kidney proximal tubule cells. Channel activity increased with hyperpolarizing membrane potentials at more positive pipette
potentials (V
p)]. Open probability (P
o) was 0.03, 0.13, and 0.21 atV
p values of 0, 40, and 80 mV, respectively. Barium (0.1 mM) in the pipette reducedP
o by 79% at aV
p of 40 mV. Application of negative hydraulic pressure (−16 to −32 cm H2O) to the pipette markedly activated outward currents (fromP
o=0.01 to 0.75) at aV
p of −80 mV, but not inward currents at aV
p of 80 mV. The size of the activated outward currents (from cell to pipette) did not change by replacing chloride with gluconate
in the pipette. These results indicate that a stretch-activated K+ channel exists in the basolateral membrane of proximal tubule cells. It may play an important role as a K+ exit pathway when the cell membrane is stretched (for example, by cell swelling). |
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Keywords: | Kidney proximal tubule Patch-clamp Stretch-activated K+ channel |
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