Contribution of the Na+ channel and Na+/H+ exchanger to the anoxic rise of [Na+] in ventricular myocytes

B. N. Eigel, R. W. Hadley

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54 Scopus citations


The aim of this study was to quantify the contribution of the Na+/H+ exchanger (NHE) and the Na+ channel to the rise in cytosolic Na+ concentration ([Na+]) that is seen in anoxic guinea pig ventricular myocytes. [Na+] was measured with the use of microfluorometry and was found to rise to 44 mM after prolonged anoxia. This rise was partially sensitive to either TTX or HOE-642, selective inhibitors of the Na+ channel and NHE1, respectively. [Na+] did not significantly rise when both drugs were present, suggesting that other routes of Na+ entry were insignificant. However, the relative contributions of the NHE and the Na+ channel were found to be remarkably sensitive to ionic conditions expected to occur during ischemia. The Na+ channel was the dominant Na+ source during acidic anoxia. However, the NHE was the dominant Na+ source during both hyperkalemic anoxia and simulated ischemia (hyperkalemia, low pH, and anoxia). The data suggest that the NHE may prove to be the best pharmacological target to reduce Na+ entry during true ischemia and that inhibition of Na+ influx could contribute strongly to the cardioprotective effects of NHE inhibitors.

Original languageEnglish
Pages (from-to)H1817-H1822
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number5 46-5
StatePublished - Nov 1999


  • Heart
  • Ischemia
  • Sodium
  • Sodium-binding benzofuran isophthalate

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)


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