Evaluation of injury preservation in pig kidney cold storage by proton nuclear magnetic resonance spectroscopy of urine

The isolated perfused kidney (IPK) model from pig was used to assess initial renal functions after cold flush and a 24- and 48-hour cold storage preservation (CSP) with Euro-Collins (EC) and to determine ischemia reperfusion (IR) impairment by biochemical, histological and proton nuclear magnetic resonance (NMR) spectroscopy of urine analysis. Eighteen pig kidneys were used. There were three experimental groups: Group 1-control kidneys flushed with cold heparinized saline, Group 2-cold flush followed by 24-hour CSP and reperfusion, Group 3-cold flush followed by 48-hour CSP and reperfusion. Kidneys were perfused for 2-hour at 37.5C for the determination of exogenous creatinine clearance (CCr), perfusion flow rate (PFR) and tubular function. Functional parameters and histological data are very poor after prolonged cold ischemia. Levels of tubular injury markers determined by proton NMR spectroscopy analysis were significantly higher with a longer ischemic time correlating well with the increased degree of renal functional and anatomic impairment. A new peak detected only in the 48-hour ischemic group was identified. In this model, proton NMR spectroscopy may be a useful technique in the evaluation of both new preservation solutions or methods.