[Energy metabolism and work capacity of skeletal muscles in patients with chronic heart disease: a study using 31P-magnetic resonance spectroscopy].
Limitation on muscle work capacity independent of blood supply has been postulated to be a contributing factor for a decrease in exercise tolerance in patients with chronic heart disease. The purpose of this study was to assess the exercise energy metabolism of skeletal muscles in chronic heart disease in relation to work capacity using 31-Phosphorus magnetic resonance spectroscopy (31P-MRS). Ten patients with chronic heart disease (group C) and 11 healthy subjects (group N) were studied. Peak oxygen uptake was determined during upright ergometer exercise. For the MRS study, the maximal cross-sectional area (MCA) of flexor muscles in the forearm and calf was first determined from MRI. Next, wrist and planter flexion exercises were performed separately while MRS spectra obtained. The exercise work load was applied according to each MCA (1J/cm2/min). Body weight and MCA were not significantly different between N and C. Peak oxygen uptake (ml/kg/min) and work rate (watt) during ergometer exercise ware significantly decreased in C (31 +/- 6 vs. 18 +/- 8 and 154 +/- 39 vs. 100 +/- 17, respectively, mean +/- SD, N vs. C, P < 0.05). In the MRS study, the decrease in pH was significantly greater in the forearm than in the calf in both groups. In comparing C with N, a decrease in PCr (suggestive of increased ADP) and a decrease in pH were greater in C in the calf. However, the peak work rates of both flexors were not significantly different between N and C. These results suggest that chronic heart disease probably affects the energy metabolism of mitochondria in skeletal muscles of the lower extremity.(ABSTRACT TRUNCATED AT 250 WORDS)
Yamada
Y
Y
Department of Cardiovascular Medicine, Hokkaido University School of Medicine, Sapporo, Japan.
D000328:Adult; D000368:Aged; D002908:Chronic Disease; D004734:Energy Metabolism / Q000502:physiology*; D016552:Ergometry; D005260:Female; D006331:Heart Diseases / Q000378:metabolism* / Q000503:physiopathology; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009132:Muscles / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*