Effect of nifedipine in the protection of renal function during in situ preservation

In an experimental study on six healthy dogs both kidneys were exposed and subjected to 1 h of ischaemia by clamping both renal vessels. To the left renal artery, 300 ml of cold (4 degrees C) Euro-Collins solution in which nifedipine (Bay a 1040--20 micrograms/kg per min) was diluted, was infused for 15 min. Simultaneously 300 ml of cold Euro-Collins solution plus 20 micrograms/kg per min of placebo (Bay a 1040--placebo) was infused in the right renal artery. The 1 h of ischaemia was divided in a 15-min period of cold ischaemia and 45 min of warm ischaemia, at the end of which both clamps were removed. During the 2 h (4 X 30 min) following the removal of the clamps, urine volume, urea and creatinine clearances, urine sodium concentration, sodium fractional excretion (%) and urine/plasma osmolality ratio measurements were made and results compared to the pre-ischaemia values. Both kidneys were then removed for histological study. The nifedipine group restored diuresis of 0.43 +/- 0.23 ml/min within 30 min, while this degree of diuresis (0.64 +/- 0.16 ml/min) was achieved by the placebo group at 120 min. Urine volume as well as creatinine and urea clearances of the nifedipine group were significantly higher in all studied periods compared to the placebo group (P less than 0.01 or P less than 0.025). Urine sodium and FENa (%) were not different between the two groups, and urine/plasma osmolality ratio was above 1.1 in all studied periods for both groups. The microscopic study did not show any significant differences between the two groups. We conclude that nifedipine is effective in the protection of renal function when it is administered during experimental in situ preservation.