Showing papers by "Paul M. Matthews published in 1985"

A phosphorus-31 nuclear magnetic resonance study of effects of altered thyroid state on cardiac bioenergetics.

Abstract: We have used 31P nuclear magnetic resonance (NMR) techniques to characterize bioenergetic changes in the Langendorff-perfused rat heart accompanying alterations in thyroid state. Cytosolic phosphocreatine and inorganic phosphate concentrations changed significantly in both the hypo- and hyperthyroid groups compared to controls; the calculated phosphorylation potential [( ATP]/[ADP][Pi]) increased by 60% in hypothyroidism and decreased by 60% in hyperthyroidism relative to the euthyroid value of 47 X 10(3) M-1. Creatine phosphokinase (CPK) and mitochondrial ATP synthase rates were measured in the intact tissue using a saturation-transfer NMR method. There were no significant differences in the measured fluxes through the CPK reaction among the three groups (4.24 +/- 1.00 mM X sec-1 for the euthyroid group). Although O2 consumption increased by 46% in hearts from hyperthyroid animals, no change in the measured mitochondrial ATP synthase flux was observed compared to the euthyroid flux of 1.05 +/- 0.11 mM X sec-1. These results suggest that the apparent in situ P/O ratio of mitochondria in hearts from hyperthyroid animals is reduced relative to that in euthyroid controls.

In vivo phosphorus-31 nuclear magnetic resonance study of the regional metabolic response to cardiac ischemia.

Abstract: We applied 31P nuclear magnetic resonance to the study of acute ischemia in vivo In open-chest rabbits, the left anterior descending coronary artery was occluded after control spectra were obtained Phosphocreatine concentration decreased in the first minute and ATP concentration declined subsequently, and pH decreased to 58 within 20 min Intracellular acidosis was greater than that previously reported for the isolated perfused rabbit heart