Citrate, acetate and renal medullary osmolyte excretion in urine as predictor of renal changes after cold ischaemia and transplantation

In organ transplantation, the determination of reliable parameters to asses s ischaemic damage is essential to predict renal injury after preservation. The aim of this study was to assess renal medullary injury by H-1 NMR (pro ton nuclear magnetic resonance) spectroscopy after preservation and reperfu sion. Three experimental groups of pigs were examined during a 2-week perio d: control group (n = 4), Euro-Collins group (EC) (cold flushed and 48 h co ld storage of kidney in EC and autotransplantation, n = 7), and University of Wisconsin (UW) group (cold flushed and 48 h cold storage of kidney in UW and autotransplantation, n = 7). Creatinine and urea were improved in the two cold stored groups. The most relevant resonances determined by H-1 NMR spectroscopy after transplantation were those arising from citrate and acet ate in urine and trimethylamine-N-oxide (TMAO) in urine and plasma. We demo nstrate that graft dysfunction is associated with damage to the renal medul la as determined by TMAO release in urine and plasma. Conversely, citrate e xcretion can discriminate kidneys with favourable outcome. This study outli nes the specific and beneficial impact of UW solution on renal preservation and suggests that H-1 NMR spectroscopy is efficient both to detect ischaem ic damage of preserved kidneys and to discriminate the preservation quality between different preservation solutions.