In Vivo Phosphorus-31 Nuclear Magnetic Resonance (NMR) Spectroscopy Of Cardiac Metabolism: Initial Observations Of Hypoxia And Adrenergic Stimulation

High resolution 31P nuclear magnetic resonance (NMR) spectroscopy has been applied to the direct, noninvasive examination of phosphorylated substrate metabolism in the myocardium of live rabbits. By the combination of field profiling gradients and a surface, or flat, NMR coil placed directly over the region of the thorax which contains the heart, spatially localized NMR measurements of metabolic function in live animals can be obtained. This technique, termed "topical magnetic resonance" or TMR, has been used to follow the effects of several physiological conditions on the tissue pH and levels of key, energy-rich phosphorylated compounds in the hearts of live, anesthetized rabbits. Changes in tissue content of adenosine triphosphate (ATP), creatine phosphate (CP), and inorganic phosphate (Pi) and the NMR line widths of these species have been observed in animals given appropriate doses of adriamycin for a five day period. These preliminary data demonstrate the potential of spectroscopic NMR techniques in the evaluation of disease states in organs and tissues within the body and the ability to monitor both toxic and therapeutic effects of drugs.