Abstract
The energy metabolism in living organs (salivary gland and inner ear) was studied by both conventional and topical 31P-nuclear magnetic resonances (NMR and TMR) as non-invasive procedures. In isolated perfused salivary glands of the rat and dog, cessation of perfusion caused the tissue level of creatine phosphate (PCr) to decrease rapidly and that of ATP to decrease moderately. Restarting the perfusion caused PCr to recover rapidly with a time constant of 40 sec. Acetylcholine (ACh; 5×10-6M) induced massive salivation and a simultaneous decrease of PCr. The removal of ACh resulted in a prompt recovery of PCr, with 45 sec of decay, to the resting value. During Na-free perfusion, even in the presence of ACh, only minimal salivation and no decrement of PCr were noted. The surface coil (1.3cm in diameter) was set on the mandibular gland of the dog, in the magnet of TMR. The results of the gland in situ were similar to those of the perfused gland. The 31P-TMR was also applied to the inner ear of the guinea pig. Resonances of PCr, ATP, ADP, inorganic phosphate and sugar phosphates were observed. Destruction of the inner ear caused these signals to disappear. By intravenous injection of furosemide did not change the resonances of PCr or ATP.
