Ca2+-activated K+ channels from cultured renal medullary thick ascending limb cells: Effects of pH

Miguel Cornejo, Sandra E. Guggino, William B. Guggino

Research output: Contribution to journalArticlepeer-review

Abstract

Ca2+-activated K+ channels were studied in cultured medullary thick ascending limb cells (MTAL) using the patch-clamp technique. The purpose was to determine the effect of acidic pH on channel properties in excised patches of apical cell membrane. At pH 7.4, increasing Ca2+ on the intracellular side or applying positive voltages increases channel open probability. Reducing pH to 5.8 on the intracellular face of the channel decreases channel open probability at each voltage and Ca2+ concentration. Channel mean open times display two distributions and mean closed times display three distributions. Increasing Ca2+ or applying depolarizing voltages lengthens each of the mean open times and shortens each of the closed times. Lowering pH to 5.8 decreases the mean open times and increases mean closed times at each Ca2+ and voltage with the greatest effect on the mean closed times. In contrast, both single-channel conductance and channel kinetics are unaffected when pH is reduced to 5.8 on the extracellular face of the membrane. We conclude that protons interfere with Ca2+ binding to the gate of Ca2+-activated K+ channels reducing the probability of channel opening.

Original languageEnglish (US)
Pages (from-to)49-55
Number of pages7
JournalThe Journal of Membrane Biology
Volume110
Issue number1
DOIs
StatePublished - Aug 1 1989

Keywords

  • acid/base balance
  • calcium
  • channels
  • loop of Henle
  • potassium secretion
  • thick ascending limb

ASJC Scopus subject areas

  • Biophysics
  • Physiology
  • Cell Biology

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