The detection of chronic heart graft rejection by P-31 NMR spectroscopy

The usefulness of phosphorus-31 nuclear magnetic resonance spectroscopy (P- 31 NMRS) for detecting heart graft rejection after transplantation has been investigated by several researchers, and it has thus been demonstrated to be a valid technique for detecting acute myocardial rejection. In this stud y, we investigated the value of P-31 NMRS to assess chronic cardiac allogra ft rejection. Lewis rat hearts were transplanted into the femoral region of F-344 rat recipients which were treated with cyclosporine, 5 mg/kg body we ight, by a daily intramuscular injection for 30 days beginning on the day o f transplantation. The control isografts employed Lewis donors and recipien ts not given cyclosporine. The ratios of phosphocreatine (PCr) to inorganic phosphate (P-i), beta-adenosine triphosphate (beta-ATP) to P-i, and PCr to beta-ATP were monitored using surface coil P-31 NMRS, P-31 NMRS was perfor med 3, 30, and 60 days after transplantation, and the degree of the rejecti on and arteriosclerosis of the coronary arteries were then assessed histolo gically. The PCr:P-i and beta-ATP:P-i ratios for the allografts demonstrate d a significant decrease on postoperative day (POD) 60 from that on POD 30 (PCr:P-i, P < 0.001; beta-ATP:P-i, P < 0.01). Although a significant differ ence existed between the isografts and allografts on POD 60 (PCr:P-i, P < 0 .01; beta-ATP:P-i, P < 0.01), no significant difference was found in the PC r:beta-ATP ratio between the allografts and the isografts, On POD 60, the a llografts showed significant graft rejection and arteriosclerotic changes i n the coronary arteries. These findings therefore demonstrated the effectiv eness of P-31 NMRS for detecting chronic graft rejection in a rat model.