Ca2+-and voltage activated K+ channel in apical cell membrane of gallbladder epithelium from Triturus

Y. Maruyama, H. Matsunaga, T. Hoshi

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


The presence of Ca2+- and voltage-activated K+ channels was directly demonstrated in the apical cell membrane of gallbladder epithelium by patch-clamp single-channel current recording. In K+-depolarized epithelial cells, negative pipette potentials induced outward current steps when the patch-pipette was filled with Na+-rich solution and these current steps were not affected by the presence or absence of Cl-. When K+-rich solution was in the pipette and K+-depolarized cells were examined, the current-voltage relations were linear with a single-channel conductance of 140 pS and polarity was reversed at 0 mV. In excised inside-out membrane patches, raising the free Ca2+ concentration of the medium facing the inner side of the membrane from 10-7 to 10-6 M evoked a marked increase in open state probability of the channels without affecting the elementary current steps. This suggests that intracellular Ca2+ as a second messenger plays a crucial role in the regulatory mechanism of the membrane potential by modulating the high-conductance apical K+ channels.

Original languageEnglish
Pages (from-to)563-567
Number of pages5
JournalPflügers Archiv European Journal of Physiology
Issue number6
Publication statusPublished - 1986 Jun 1


  • Apical cell membrane
  • Ca activation
  • Gallbaladder
  • K channel
  • Patch-clamp
  • Voltage activation

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)


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