In vivo 31P NMR studies of rat salivary glands at 6.3 tesla.

In vivo 31P NMR spectra of rat submandibular glands were obtained. The glands were exposed, leaving the neurovascular system intact, and placed in a solenoidal coil. Resonances of nine phosphate metabolites were identified in the spectra and metabolite concentrations were estimated from the corresponding integrals ([ATP] = 3.4 +/- 0.7 mM). Tissue pH, as deduced from the chemical shift of the inorganic phosphate resonance, was 7.26 (+/- 0.07). T1 relaxation times of ATP, phosphocreatine, inorganic phosphate, and phosphomonoester 31P spin systems were examined. The effect of hypoxia was followed as a function of time. 31P NMR spectra of the glands have also been obtained noninvasively by the use of a surface coil, adapted to the dimensions of the glands, and depth pulses.