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
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.