Acid incubation increases NHE-3 mRNA abundance in OKP cells

M. Amemiya, Y. Yamaji, A. Cano, O. W. Moe, R. J. Alpern

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92 Scopus citations


With the use of degenerate primers based on conserved amino acid sequences in human, rat, and rabbit Na/H exchanger-3 (NHE-3), a polymerase chain reaction product was obtained from reverse-transcribed OKP (a clonal opossum kidney cell line) mRNA and used to screen an OKP cDNA library. The clone obtained predicted an amino acid sequence that was 86% identical to rat NHE- 3, 33% to NHE-1, 35% to NHE-2, and 30% to NHE-4. Expression of the corresponding cRNA in Xenopus oocytes induced 22Na uptake with ethylisopropylamiloride (EIPA) resistance similar to that of the OKP Na/H antiporter. On RNA blot, the cDNA labeled a 9.5-kb transcript whose abundance was increased 2.2-fold by 24-h incubation of OKP cells at pH 7.0 and 2.5- fold by 24-h incubation at pH 6.8. The acid-induced increase in NHE-3 mRNA was detectable at 12 h and increased further at 24 h. Incubation in acid media caused an increase in EIPA-resistant Na/H antiporter activity that preceded the increase in NHE-3 mRNA. In summary, OKP cells express an NHE-3 transcript that encodes an EIPA resistant Na/H antiporter and is chronically regulated by acid.

Original languageEnglish (US)
Pages (from-to)C126-C133
JournalAmerican Journal of Physiology - Cell Physiology
Issue number1 38-1
StatePublished - 1995


  • acidosis
  • ethylisopropylamiloride
  • oocyte expression
  • sodium/proton antiporter

ASJC Scopus subject areas

  • Physiology
  • Cell Biology


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