Proton NMR Spectroscopy as a Novel Approach to the Assessment of Function in the Pig Isolated Kidney Exposed to Cold Ischemia

Abstract

High-resolution proton nuclear magnetic resonance (NMR) spectroscopy can be used to detect and quantify low molecular weight metabolites in biological fluids. The purpose of this study was to analyse the urine and perfusate with an isolated perfused kidney after cold storage (CS) from large white pigs by NMR spectroscopy. Kidneys were flushed in situ and cold stored with Euro-Collins (EC) and University of Wisconsin (UW) solutions. Two groups were studied: A (n=8; CS for 48-hour with EC) and B (n=8; CS for 48-hour with UW). Reperfusion was performed at 37°C for 2-hour via renal artery with a freshly prepared Krebs solution with creatinine (10mg/L), bovine serum albumine (5%), amino acids mixture of 22 L-amino acids in concentrations between 0.2 and 2.0 mmol/L and oxygenated by O2: 95%-CO: 25%. Perfusate flow rate (PFR) was adjusted during reperfusion to maintain mean arterial pressure at 100 mm Hg. samples were collected at 15, 30, 45, 60, 90 and 120 minutes during perfusion for biochimical and NMR analysis in urine and perfusate. Optical and electronical microscopy was performed after cold storage and reperfusion. PFR is greater in B (p<0.001) related with less intense edema and vascular constriction. Creatinine clearance is lower in A (p<0.001). Fractional reabsorption of sodium is significantly greater in B. LDH and N-acetyl BD glucosaminidase excretion are more important in A (p<0.01).