Control of steady-state intracellular ph in intact perfused ferret hearts

Hideo Kusuoka, Eduardo Marban, Horacio E. Cingolani

Research output: Contribution to journalArticlepeer-review

Abstract

To elucidate the role of bicarbonate-dependent mechanisms and Na+/H+ exchange in maintenance of physiological intracellular pH (pHi) under various steady-state conditions, phosphorus NMR spectra were taken in isovolumically-contracting, perfused ferret hearts. Switching the perfusate from HCO3−/CO2 to HEPES buffer significantly decreased pHi from the control value of 7.14 ± 0.01 (mean ± S.E., n = 4) to 7.08 ± 0.01 (P < 0.01). Exposure to 4-acetamide-4′-isothiocyanatostilbene-2.2′-disulphonic acid (SITS: 10−4 M) a blocker of anion exchange (7.12 ± 0.01 in control, 7.07 ± 0.02 with SITS, n = 6, P < 0.05), led to acidification of pHi. Ethylisopropylamiloride (EIPA: 10−6 M), a blocker of the Na+/H+ exchange, induced a decrease in pHi (7.17 ± 0.01 in control, 7.11 ± 0.01 with EIPA, n = 5, P < 0.05). Lowering [Cl] in the perfusate (7.14 ± 0.02 in control, 7.09 ± 0.03 with low-[Cl]0 perfusate, n = 5, P < 0.01) also decreased pHi, perhaps by a non-bicarbonate-dependent mechanism. These results indicate that both bicarbonate-dependent mechanisms and Na+/H+ exchange contribute significantly and additively to the maintenance of physiological pHi in isovolumically contracting, perfused hearts.

Original languageEnglish (US)
Pages (from-to)821-829
Number of pages9
JournalJournal of Molecular and Cellular Cardiology
Volume26
Issue number7
DOIs
StatePublished - Jul 1994

Keywords

  • Na/H exchange
  • Na/HCO
  • Na−dependent Cl/HCO exchange
  • Na−independent Cl/HCO exchange
  • Phosphorus NMR

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine

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