Preincubation in acid medium increases Na/H antiporter activity in cultured renal proximal tubule cells

Shigeo Horie, Orson Moe, Alberto Tejedor, Robert J. Alpern

Research output: Contribution to journalArticle

73 Scopus citations

Abstract

Chronic acidosis in vivo leads to an increase in proximal tubule Na/H antiporter activity that persists when the transporter is studied out of the acidotic environment. It is presently not clear whether a decrease in extracellular fluid pH alone is sufficient to elicit this adaptation. The present studies examined the effect of acid preincubation on Na/H antiporter activity in cultured proximal tubule cells. Antiporter activity was examined after a 2-day preincubation in control or acid medium, 1 hr after removal from the preincubation fluid. Na/H antiporter activity was assayed as the initial rate of Na-dependent alkalinization after cell acidification in the absence of CO2/HCO3. Preincubation in low [HCO3] acid medium or in high PCO2 acid medium led to increases in amiloride-sensitive Na/H antiporter activity. This adaptation was inhibited by addition of cycloheximide to the preincubation medium. Preincubation of fibroblasts in low [HCO3] acid medium did not lead to increased Na/H antiporter activity but rather caused a small inhibition. These studies demonstrate an adaptation in Na/H antiporter activity elicited by a low pH of the extracellular fluid, which is dependent on protein synthesis, and may be unique to certain H/HCO3-transporting epithelia.

Original languageEnglish (US)
Pages (from-to)4742-4745
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Volume87
Issue number12
DOIs
StatePublished - 1990

Keywords

  • acidosis
  • cycloheximide
  • cytoplasmic pH
  • fibroblast

ASJC Scopus subject areas

  • General

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