Phosphorus nuclear magnetic resonance studies on normoxic and ischemic cardiac tissue.

Abstract

The intact heart of a young rat was excised rapidly and cooled to 0.degree. C; its energy-rich compounds were examined by 31P Fourier Transform NMR. The heart showed the characteristic spectrum of sugar phosphates, inorganic phosphate, phosphocreatine and magnesium ATP, characteristics of the energizing state of the nonbeating tissue. Warming to 30.degree. C imposes an energy load upon the heart consistent with short-term resumption of beating, concomitant intracellular acidosis and decomposition of all detectable energy-rich compounds. The intracellular acidity caused a shift from pH 7.0 to 6.0. The effects of possible interferences with this pH measurement were considered. The method appeared to be useful in cardiac infarct models for detecting the fraction of the total volume occupied by the infarct and for studying the effect of various proposed therapies upon this infarcted volume.