P-31 NMR KINETICS STUDY OF CARDIAC METABOLISM UNDER MILD HYPOXIA

Citation
Jf. Goudemant et al., P-31 NMR KINETICS STUDY OF CARDIAC METABOLISM UNDER MILD HYPOXIA, Journal of magnetic resonance. Series B, 106(3), 1995, pp. 212-219
Citations number
48
Categorie Soggetti
Physics, Atomic, Molecular & Chemical
ISSN journal
10641866
Volume
106
Issue
3
Year of publication
1995
Pages
212 - 219
Database
ISI
SICI code
1064-1866(1995)106:3<212:PNKSOC>2.0.ZU;2-7
Abstract
The effects of mild hypoxia on the metabolic and mechanical functions of isovolumic perfused rat hearts have been studied. P-31 NMR has been used to follow the metabolite concentrations as well as the intracell ular pH. Additionally, the energy transfer through the creatine kinase reaction was estimated by the magnetization-transfer technique. The n eeds of myofibrillar energy and of mitochondrial ATP production have b een assessed through mechanical activity and oxygen-consumption rate. It has been observed that mild hypoxia simultaneously impairs contract ile and metabolic functions. The aerobic ATP production is maintained under these conditions while anaerobic energy metabolism seems acceler ated. The accumulation of some metabolites (ADP and P-i) and the decre ase of creatine kinase forward flux (V-for) tend, however, to prove th at ATP availability for myofibrils is lowered. The large aerobic energ y production observed must therefore be explained by an energy wastage in the mitochondria. In spite of normal ATP concentration, a contract ile dysfunction is observed and can be explained by the P-i accumulati on, which is known to impair the use of the myofibrillar ATP. Another hypothesis supported by the magnetization transfer experiments is the poor ATP availability resulting from the ATP wastage in the mitochondr ia and from the inefficient energy transport by the PCr-Cr shuttle. (C ) 1995 Academic Press, Inc.