Stability of high-energy phosphates in right ventricle: Myocardial energetics during right coronary hypotension

Masao Itoya, Robert T. Mallet, Zhi Ping Gao, Arthur G. Williams, H. Fred Downey

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Abstract

This study was conducted to determine if mechanisms that reduce right coronary (RC) blood flow (RCBF) and right ventricular (RV) oxygen consumption (MV̇O2) during moderate RC hypotension preserve RV high-energy phosphates. RC arteries of anesthetized dogs were cannulated and perfused with arterial blood supplied by a pressurized extracorporeal circuit. RC perfusion pressure (RCPP) was either kept constant at 100 mmHg or reduced to 60 or 30 mmHg for 20 min followed by a freeze-clamp biopsy of RV. Left ventricular (LV) biopsy was also performed to compare energy metabolism between RV and LV. RCBF and MV̇O2 significantly decreased when RCPP was reduced to 60 mmHg, but RV segment shortening (%SS) was unchanged; ATP, creatine phosphate (CrP) and phosphorylation state of CrP ([CrP]/[Cr][Pi]) did not differ from control values. RV %SS, CrP, and phosphorylation state fell markedly at 30 mmHg RCPP. At 100 mmHg RCPP, CrP phosphorylation state in RV was only 35% of that in LV. These results indicate that RV increases its energetic efficiency without significant changes in high-energy phosphates or CrP phosphorylation state during moderate RC hypotension. Furthermore, the RV myocardium maintains a much lower energy level than LV myocardium, commensurate with its lower energy requirements.

Original languageEnglish
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume40
Issue number1
Publication statusPublished - 1 Jul 1996

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Keywords

  • Coronary perfusion pressure
  • Creatine phosphate
  • Myocardial oxygen consumption
  • Oxygen utilization efficiency

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