Adaptation to chronic hypoxia alters cardiac metabolic response to β stimulation: Novel face of phosphocreatine overshoot phenomenon

The dynamics of the changes in myocardial phosphorylated compound contents (inorganic phosphate: Pi; phosphocreatine: PCr; ATP) induced by 10 −6 m isoprenaline administration was studied, using 31P-NMR spectroscopy, in hearts isolated from rats adapted for three weeks to normobaric hypoxia (10% of o...

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Bibliographic Details
Published in:Journal of molecular and cellular cardiology 1995-08, Vol.27 (8), p.1679-1687
Main Authors: Novel-Chaté, Valerie, Aussedat, Jean, Saks, Valdur A., Rossi, Andre
Format: Article
Language:English
Subjects:
Acclimatization
Adaptation
Adenosine Diphosphate - metabolism
Adenosine Triphosphate - metabolism
Adrenergic beta-Agonists - pharmacology
Animals
Chronic Disease
Chronic hypoxia
Female
Heart - drug effects
Heart - physiology
Heart - physiopathology
Hypoxia - metabolism
Isoprenaline
Isoproterenol - pharmacology
Kinetics
Magnetic Resonance Spectroscopy
Myocardial Contraction - drug effects
Myocardium - metabolism
Oxygen Consumption
Phosphates - metabolism
Phosphocreatine - metabolism
Phosphocreatine overshoot
Rats
Rats, Wistar
Reference Values
Space life sciences
Time Factors
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Summary:The dynamics of the changes in myocardial phosphorylated compound contents (inorganic phosphate: Pi; phosphocreatine: PCr; ATP) induced by 10 −6 m isoprenaline administration was studied, using 31P-NMR spectroscopy, in hearts isolated from rats adapted for three weeks to normobaric hypoxia (10% of oxygen). When compared with the behaviour of control hearts, the inotropic response to Ca 2+ and isoprenaline was larger in the hearts from hypoxic rats, while the oxygen consumption was similar. During administration of isoprenaline, a decrease in the myocardial contents of high energy phosphates (ATP and PCr) and an accumulation of Pi was observed in both groups. After action of isoprenaline, the hearts from hypoxic animals showed significant overshoot of PCr, that was not seen in hearts from normoxic rats. The mechanisms of these alterations are analysed and the phosphocreatine overshoot, as well as the increased rate pressure product to oxygen consumption ratio, are assumed to indicate more efficient energy conversion in the heart from animals adapted to chronic hypoxia.
ISSN:0022-2828
1095-8584
DOI:10.1016/S0022-2828(95)90755-6