31P-NMR investigation of solid tumours in the living rat.

The 31P-NMR spectra of living tumours (Walker 256 carcinosarcomas) have been obtained using surface coils and found to be unlike those of normal tissues. Contrary to expectations, their intracellular pH (measured from the chemical shift of the inorganic phosphate peak) was only slightly more acid than that of normal rat muscle, and glucose infusion did not depress it. However, when deoxyglucose was infused, the tumour intracellular pH measured from the chemical shift of the deoxyglucose-6-phosphate peak was much lower (6.44 +/- 0.02) than that measured from the phosphate peak (7.14 +/- 0.01).