A comparison of the relative effectiveness of three transplant preservation fluids upon the integrity and function of rabbit proximal convoluted tubules perfused in vitro.

Rabbits were anaesthetized and kidneys removed directly with no flush (group NF), or alternatively kidneys were flushed (group F) with sodium phosphate buffered 140 mmol/l sucrose (PBsuc 140), Collins C2 (C2) or Euro-Collins (EC) transplant preservation solutions and stored at 4 degrees C for 0-4, 24 or 48 h. Mid-cortical proximal convoluted tubule (PCT) segments were dissected from all groups and set up for microperfusion in vitro. Observations were made of tubule morphology, fluid reabsorption rate (Jv), bath leak of the glomerular marker iothalamate and transmural potential difference (p.d.), both at 37 degrees C and at 15-20 degrees C, in order to compare the relative effectiveness of the solutions in the preservation of tubule integrity and immediate function. Tubules from kidneys flushed with EC and C2 contained luminal debris and frequently had high bath leaks of iothalamate, both indicative of poor preservation of tubule integrity. In contrast, tubules from NF kidneys and PBsuc 140-flushed kidneys were free of luminal debris with a lower incidence of high iothalamate leaks. Tubules from PBsuc 140-flushed and EC-flushed kidneys after 0-4 and 24 h storage had Jv that were similar to those of NF kidneys. Tubules from all groups of flushed kidneys after 48 h cold storage and all tubules from C2-flushed kidneys showed reduced Jv values. In all cases Jv was reduced to approximately zero when the temperature was lowered to 15-20 degrees C. Transmural p.d. was similar in all groups except for particularly low p.d. values observed in tubules from C2-flushed kidneys after 48 h storage. These observations suggest that PBsuc 140 is more effective in the preservation of tubule function during prolonged cold storage than the glucose-based Collins solutions. The marked difference in the effectiveness of C2 and EC contraindicates the inclusion of magnesium (present in C2) for preservation of kidneys, as judged by experiments on the rabbit.