Bioenergetic effects of repeated +Gz acceleration on rat heart: a 31P-NMR study on isolated hearts.
This investigation was designed to determine whether repeated exposure to high sustained +Gz acceleration induces persisting changes in the myocardial energetic metabolism. Rats were exposed to three plateaus of 30 s at 10 +Gz, four times a week, for 4 weeks. Myocardial concentrations of high-energy phosphorylated compounds were evaluated by 31P-nuclear magnetic resonance (NMR) spectroscopy on isolated hearts submitted to isovolumic aortic perfusion. Heart performances were recorded using the intraventricular balloon method. Compared to the hearts of control rats (n = 5), the hearts of centrifuged rats (n = 5) had higher concentrations of inorganic phosphate (Pi:1.40 +/- 0.33 nM vs. 0.36 +/- 0.07 mM; p < 0.01), decreased phosphocreatine concentrations (PC:15 +/- 0.39 mM vs. 15.69 +/- 0.19 mM; p < 0.01), and a lower left ventricular developed pressure (LVDP) (21 +/- 1 mmHg vs. 34 +/- 2 mmHg; p < 0.01). The workload was increased by sequential augmentation of calcium in the perfusion medium. The relationship between LVDP and the Pi/PC ratio showed that the cost of the cardiac work was greater for the centrifuged rats.
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Institut de Médecine Aérospatiale du Service de Santé des Armées, Brétigny-sur-Orge, France.
Aussedat
J
J
Ray
A
A
Lortet
S
S
Rossi
A
A
Quandieu
P
P
D000818:Animals; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D006321:Heart / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D018471:Hypergravity / Q000009:adverse effects*; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging; D010759:Phosphorus Isotopes; D051381:Rats; D017208:Rats, Wistar; D017725:Ventricular Pressure / Q000502:physiology*
D010759:Phosphorus Isotopes