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31P NMR was used to study the systemic effects of a tumor on a host organism by monitoring the phosphate metabolite content in freshly excised mouse liver at 0-4 degrees C and in ethanolic liver extracts of animals suffering from La, L1210 and P388 leukemias and Ehrlich ascites tumor (EAT). The progression of murine leukemia is characterized by increases in the intensities of the resonances of Pi and phosphomonoesters (PME), in particular, phosphorylethanolamine, in liver; phosphodiester (PDE) signals increase two- to four-fold during the period of rapid tumor growth and decline to undetectable levels in the terminal stage. There were no reliable alterations detected in the ATP content and intracellular pH throughout the course of the leukemia. The kinetics of intracellular phosphates are similar in various kinds of leukemia but quite different in EAT. The reduction of inoculum causes the appearance of maxima in the Pi and PME profiles in the latent period of La leukemia, but the profiles of liver PDE considered from the end of the latent period are independent of inoculum. Possible mechanisms for the changes in PDE concentrations and their biochemical role are discussed. NMR spectroscopy of liver may be used to indirectly monitor the progression of tumors unavailable for direct NMR assay.

In order to study the effects of epinephrine and insulin on liver metabolism, measurements of cellular phosphates and intracellular pH by 31PNMR, of glycogen by 13C NMR and of lactate by 1H NMR were performed in freshly dissected mouse liver at 0-4 degrees C and in ethanolic liver extracts. The injection of epinephrine hydrochloride (0.1 mL of 0.1% solution i.p. per mouse) caused remarkable changes in liver metabolic profiles which were expressed most distinctly in 15-30 min and could not be attributed solely to epinephrine-induced hyperglycemia. Among these metabolic changes are falls in the levels of ATP and uridine diphosphate sugars by 60-70%, possibly related to glycogen depletion, and intracellular acidification by 0.5 units attributed to the release of protons during hydrolysis of ATP rather than to accumulation of lactate in anaerobic glycolysis. Insulin injected prior to epinephrine (4 units i.p.) markedly suppressed epinephrine-induced metabolic alterations, although the effect of the combination of insulin and epinephrine was not the sum of the separate effects of these hormones. The maximum protective effect of insulin was reached when insulin was injected 15 min prior to epinephrine. The results obtained demonstrate the applicability of NMR for evaluating the protective activity of modifiers at various extreme exposures.

A combination of ESR and 3tp NMR techniques was used to study the mechanism of the radiosensitizing influence of misonidazole (MISO) on mouse tumors and liver. The MISO injection (1 g/kg) was shown to cause signi¡ metabolic changes in tumors, such as ah increase in the content of nitrosyl complexes, increases in adenosine diphosphate and inorganic phosphate levels, and decreases in phosphomonoesters, phosphodiesters, adenosine triphosphate and phosphocreatine in the initial period of observation. These alterations were accompanied by slight cytosol alkalinization (pH shift ca 0.15). A decrease in the ESR signal intensity of MoS+-containing enzymes, an increase in the cytochrome P-450 signal anda significant increase in the free radical signal were observed in liver after MISO treatment. Local irradiaª of tumors (30 Gy) 30 min after MISO injection led to the enhancement and prolongation of nearly all the effects induced by MISO treatment. The combined effect of MISO and irradiation was not simply the sum of their separate effects. It is suggested that radiation enhances cytotoxic effects of nitrocompounds on hypoxic tumor cells, intª glycolysis and inducing greater production of toxic and highly reactive intermediates resulting from incomplete nitro group reduction. The latter appears to be considered as the major factor involved in the radiosensitizing action of nitrocompounds.