P-31 NMR ASSESSMENT OF ORTHOTOPIC LIVER REJECTION IN A RAT MODEL

P-31 NMR spectroscopy was used serially to study rejecting (ACI-->LEW) and nonrejecting (ACl-->ACl) orthotopic liver transplants in rats. Re cipients were evaluated on post-transplant days 1, 3, 5, 7, 9, and 11. The relative changes in phosphomonoester (PME), inorganic phosphate ( P-i), high-energy phosphates and pH were studied. The earliest signifi cant difference between the rejecting and nonrejecting groups was a de crease in the alpha-NTP peak area on Day 5. This was followed by signi ficant decreases in beta-NTP and pH, and increases in PME and P-i on D ay 7. High-resolution P-31 NMR spectra of perchloric acid extracts dem onstrated the PME increase to be due mainly to elevated phosphoethanol amine. Using the parameter (P-i + PME)/(alpha + beta + gamma-NTP), rej ecting livers were distinguished from nonrejecting livers at a moderat e stage of rejection.