Influence of retrieval conditions on renal medulla injury: Evaluation by proton NMR spectroscopy in an isolated perfused pig kidney model

Background. Delayed graft function (DGF) has remained an important complica tion after renal transplantation. The exact causes of DGF remain to be clar ified, particularly the impact of retrieval conditions and preservation fac tors. In the present investigation, (HNMR)-H-1 spectroscopy of urine was as sessed in order to detect the influence of retrieval condition on renal med ulla damage. Methods. The isolated perfused pig kidney (IPK) was used to assess initial renal function from multiorgan donors (MOD) or single organ donors (SOD) af ter in situ cold hush and 24-h cold storage (CS) preservation with two stan dard preservation solutions: Euro-Collins (EC) and University of Wisconsin (UW) solutions. Kidneys hushed with cold heparinized saline and immediately perfused were used as the control group. Kidneys were perfused for 90 min at 37.5 degrees C for functional evaluation. During reperfusion, renal perf usion how rate (PF) was measured. Glomerular filtration rate (GFR), tubular reabsorption of Na+, and lactate dehydrogenase (LDH) and N-acetyl-beta-D-g lucosaminidase (NAG) excretions were determined. Ischemia-reperfusion impai rment was also determined by histological techniques and (HNMR)-H-1 spectro scopy. Results. PF, GFR, and tubular reabsorption of Na+ were significantly decrea sed in experimental groups when compared to the control group but there was no significant difference between experimental SOD groups, GFR was signifi cantly greater in UW-MOD than in EC-MOD and tubular reabsorption of Na+ was significantly greater in UW-MOD than in EC-MOD after 45 min of reperfusion . The release of LDH in the effluent and the urinary excretion of NAG were not significantly different after 24-h CS in the various experimental group s. The most relevant resonances determined by (HNMR)-H-1 spectroscopy were citrate, trimethylamine-N-oxide, lactate, acetate, and amino acids. Excreti on of these markers was significantly different when compared to biochemica l markers. A resonance (P) detected particularly in EC-MOD after 24-h CS wa s identified and well correlated to renal dysfunction. Histological study s howed that ultrastructural damage and mitochondrial injury were more pronou nced in the EC-MOD group. Conclusion. These results show that retrieval condition influences renal me dullary damage. NMR spectroscopy, which is a noninvasive and nondestructive technique, is more efficient in assessing renal damage than conventional h istology and biochemical analysis. (C) 2000 Academic Press.