The uptake of hippuran in kidney slices employed as a viability test

125J Hippuran uptake in slices from rabbit kidneys was measured in kidneys damaged by warm ischaemia alone as well as by warm ischaemia combined with 24 hours of cold ischaemia. The Hippuran uptake was calculated as the ratio between radioactivity in the slices and the activity in the incubation medium as a slice/medium ratio (S/M). S/M was unchanged after 15 minutes, 30 minutes and 1 hour of warm ischaemia, while in kidneys exposed to 2 hours of warm ischaemia a 15% decrease in S/M ratio compared with control values was noted. A 53% decrease was observed after 3 hours of warm ischaemia and 73% and 91% after 4 and 5 hours respectively. Twenty-four hours of cold ischaemia alone did not alter the Hippuran uptake, but prolonging this with 15 minutes of warm ischaemia precipitated a significant fall (25%) in S/M. This value remained constant during the first hour of warm ischaemia, but a fall of 64% was observed after 2 hours of warm and 24 hours of cold ischaemia. These findings were in agreement with experiments on kidneys damaged by arterial occlusion and recirculated. Two hours of warm ischaemia was the maximal damage the kidneys could endure and still regain normal function. After simple preservation methods with Collins solution for 24 hours, 1 additional hour of warm ischaemia was the maximal ischaemic damage the kidney was able to withstand. Hippuran uptake in kidney slices appears to be well correlated to the kidneys' ability to regain normal function after ischaemic damage.