An increase in intracellular [Na+] during Ca2+ depletion is not related to Ca2+ paradox damage in rat hearts

M A Jansen, C J Van Echteld, T J Ruigrok

Research output: Contribution to journalArticlepeer-review

Abstract

Ca2+ paradox damage has been suggested to be determined by Na+ entry during Ca2+ depletion and exchange of Na+ for Ca2+ during Ca2+ repletion. With the use of 23Na nuclear magnetic resonance, we previously observed a Ca2+ paradox without a prior Na+ increase. We have now demonstrated a Na+ increase during Ca2+ and Mg2+ depletion without the occurrence of the Ca2+ paradox during Ca2+ repletion. Isolated rat hearts were perfused for 20 min with a Ca(2+)-free or a Ca(2+)- and Mg(2+)-free (Ca2+/Mg(2+)-free) solution under hypothermic conditions (20 and 25 degrees C). Intracellular Na+ concentration ([Na+]i) increased from 11.9 +/- 1.2 to 26.9 +/- 5.8 mM (P < 0.001) during Ca2+/Mg(2+)-free perfusion at 20 degrees C, whereas no significant change in [Na+]i occurred during 20 min of Ca(2+)-free perfusion at 20 degrees C. In addition, we confirmed that [Na+]i did not change significantly during 20 min of normothermic Ca(2+)-free perfusion. Creatine kinase release during normothermic Ca2+ repletion in the 20 degrees C groups was approximately 10% and in the 25 degrees C groups 75% of the release in the normothermia group. Recovery of rate-pressure product was approximately 50% in the 20 degrees C groups versus 0% in the normothermia group. In conclusion, hypothermic Ca2+/Mg(2+)-free perfusion results in a significant increase of [Na+]i, which does not contribute to the extent of the Ca2+ paradox on normothermic Ca2+ repletion.

Original languageEnglish
Pages (from-to)H846-52
JournalAmerican Journal of Physiology
Volume274
Issue number3 Pt 2
Publication statusPublished - Mar 1998

Keywords

  • Animals
  • Calcium
  • Cold Temperature
  • Creatine Kinase
  • Heart
  • In Vitro Techniques
  • Male
  • Nuclear Magnetic Resonance, Biomolecular
  • Perfusion
  • Rats
  • Rats, Wistar
  • Reperfusion Injury
  • Sodium

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