Perfused Organs and Intact Tissues in SITU *
31P nuclear magnetic resonance (NMR) is proving to be extremely usefui in the investigation of energy metabolism in perfused and superfused isolated organ systems. It has the advantage of being nondestructive, so that in certain systems energy metabolism may be observed as an ongoing process in living tissue. 31P NMR spectra of slow and fast skeletal muscle should be considered separately. In fast skeletal muscles, ATP and PCr are usually the only appreciable peaks. Most literature on 31P NMR studies of the heart centers on ischemia/recovery, a subject of vital importance to cardiologic management. The potential benefit of a sensitive and specific test of cardiac ischemia and infarction is enormous. Most of the 31P NMR studies of intact liver to date involved monitoring of ATP and P1 levels under conditions of ischemia, starvation, and fructose infusion. In 1979, McLaughlin et al.21 were able to obtain usable 31P spectra in only 1 min from isolated perfused mouse livers.