Pathophysiological investigation of respiratory failure;Changes in energy metabolism using ^<31>P-NMR method

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1. To investigate the cellular acclimatization of energy metabolism to chronic hypoxia, concentration of high energy phosphate compounds of cultivated alveolar and peritoneal macrophages were measured by Luciferin-Luciferase methods. ATP contained 1mg of protein in alveolar and peritoneal macrophages was not significantly different. Alveolar macrophages were cultivated for 48 hr. under aerobic and anaerobic conditions. ATP in anaerobically cultivated macrophage is decreased by 20% compared with aerobically cultivated one. Creatine phosphate (CP) and energy charge were not significantly different. These results suggest that production of ATP is decreased in anaerobically cultivated macrophages due to inhibition of oxidative phosphorylation.2. Wister rats were exposed to normobaric hypoxic condition for 6 W. High energy phosphate compounds of upper thigh muscle in control and hypoxic rats were measured by Luciferin-Luciferase methods and ^<31>P-NMR spectroscopy. There is no difference of high energy phosphate compounds between control and hypoxic rats in both methods.3. Normal subject and patients with chronic respiratory failure were studied for the changes of high energy phosphate compounds during exercise. These subjects placed their arm into the magnet of the NMR spectroscopy and were asked to contract isotonically for 3 min. ^<31>P-NMR spectrum were taken every 3 min at rest, during exercise and recovery. During exercise, peak of inorganic phosphate increased and deviated to CP peak, and the CP peak decreased. In patients with chronic respiratory failure, intracellular PH decreased more remarkably than normal subject, CP/Pi during exercise was lower than that in normal subject. These results indicate that anaerobic metabolism in the patients may be activated more during exercise than in normal subject.