Na+-Ca2+ exchanger of rat proximal tubule: Gene expression and subcellular localization

J. H. Dominguez, M. Juhaszova, S. B. Kleiboeker, C. C. Hale, H. A. Feister

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

The activity of the Na+-Ca2+ exchanger, a membrane transporter that mediates Ca2+ efflux, has been described in amphibian and mammalian renal proximal tubules. However, demonstration of cell-specific expression of the Na+-Ca2+ exchanger in proximal renal tubules has been restricted to functional assays. In this work, Na+-Ca2+ exchanger gene expression in rat proximal tubules was characterized by three additional criteria: functional assay of transport activity in membrane vesicles derived from proximal tubules, expression of specific Na+-Ca2+ exchanger protein detected on Western blots, and determination of specific mRNA encoding Na+-Ca2+ exchanger protein on Northern blots. A new transport activity assay showed that proximal tubule membranes contained the highest Na+-Ca2+ exchanger transport activity reported in renal tissues. In dog renal proximal tubules and sarcolemma, a specific protein of ~70 kDa was detected, whereas in rat proximal tubules and sarcolemma, the specific protein approximated 65 kDa and was localized to the basolateral membrane. On Northern blots, a single 7-kb transcript isolated from rat proximal tubules, whole kidney, and heart hybridized under high-stringency conditions with rat heart cDNA. These data indicate that Na+-Ca2+ exchanger protein expressed in rat proximal tubule is similar, if not identical, to the cardiac protein. We suggest that the tubular Na+-Ca2+ exchanger characterized herein represents the Na+-Ca2+ exchanger described in functional assays of renal proximal tubules.

Original languageEnglish (US)
Pages (from-to)F945-F950
JournalAmerican Journal of Physiology - Renal Fluid and Electrolyte Physiology
Volume263
Issue number5 32-5
StatePublished - Jan 1 1992

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Keywords

  • calcium efflux
  • sodium-calcium exchanger

ASJC Scopus subject areas

  • Physiology

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