Background. The aim of this study was to examine whether 31P NMR can efficiently detect X-ray radiation induced changes of energy metabolism in mice. Exposure to ionizing radiation causes changes in energy supply that are associated with the tissue damage because of oxidative stress and uncoupled oxidative phosphorylation. This has as a consequence decreased phosphocreatine to adenosine triphosphate ratio (Pcr/ATP) as well as increased creatine kinase (CK) and liver enzymes (transaminases AST and ALT) levels in serum.
Materials and methods. In this study, experimental mice that received 7 Gy of X-ray radiation and a control group were studied by 31P NMR spectroscopy and biochemically by measuring CK and liver enzyme levels in plasma. Mice (irradiated and control) were measured at regular time intervals for the next three weeks after the exposure to radiation.
Results. A significant change in the Pcr/ATP ratio, determined from corresponding peaks of 31P NMR spectra, was observed in the 7 Gy group 2 days or more after the irradiation, while no significant change in the Pcr/ATP ratio, was observed in the control group. This result was supported by parallel measurements of CK levels that were highly increased immediately after the irradiation which correlates with the observed decrease of the Pcr/ATP ratio and with it associated drop of muscle energy supply.
Conclusions. The 31P NMR measurements of the Pcr/ATP ratio can in principle serve as an instantaneous and non-invasive index for assessment of the received dose of irradiation.
