Modes of operation of an electroneutral Na+/Li+ countertransport in human skin fibroblasts

Gianpaolo Zerbini, Ruggero Mangili, Daniela Gabellini, Guido Pozza

Research output: Contribution to journalArticle

Abstract

An elevated activity of erythrocyte Na+/Li+ countertransport (SLC) is an intermediate phenotype of human essential hypertension, but cells other than erythrocytes have not been studied. Therefore, we have examined several transport modes of Na+/Li+ exchange in human skin fibroblasts. External Na+-stimulated Li+ efflux was 152 ± 31 (SE) nmol · mg protein-1 · min-1 (n = 8). At intracellular pH7.3, intracellular Na+-stimulated Li+ influx, intracellular Li+-stimulated Na+ influx, and external Li+- stimulated Na+ efflux were very similar, indicating the presence of a tightly coupled 1:1 SLC. This pathway was not affected by 5-(N,N-dimethyl)- amiloride and changes in the membrane potential, but phloretin and intracellular acidification (intracellular pH 6.8) were markedly inhibitory. Kinetic analyses of the external Na+ site also compared with SLC, although the internal site appeared to show a low affinity for Li+. We conclude that an SLC pathway similar to that in human erythrocytes is expressed in human skin fibroblasts.

Original languageEnglish
JournalAmerican Journal of Physiology - Cell Physiology
Volume272
Issue number4 41-4
Publication statusPublished - 1997

Keywords

  • amiloride
  • phloretin
  • sodium/hydrogen exchange

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology
  • Physiology
  • Physiology (medical)

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