1. This study examined whether the severity of acute renal failure seen within 4 h of a 45 min period of unilateral occlusion of the renal pedicle could be reduced by removal of the contralateral healthy kidney and/or intrarenal flush with a phosphate-buffered sucrose (PBS50) solution.
2. After ischaemia, unflushed kidneys became oliguric and isosthenuric, with a fall in inulin clearance (Cin) to 0.1% of the pre-ischaemic value. Removal of the healthy contralateral kidney upon release of the occlusion caused no improvement in immediate post-ischaemic function.
3. Intrarenal flush with 1.5 ml of PBS50 resulted in a significantly improved post-ischaemic Cin, with increased urine flow rate and solute excretion; urine was also concentrated.
4. Protection of renal function against ischaemic damage was seen only when kidney tissue remained blood-free and exposed to PBS50 throughout the period of ischaemia, and when the speed of flush was similar to the expected renal blood flow (6 ml/min). Protection did not depend upon the presence or absence of the contralateral kidney.
5. The study also showed that functional removal of one kidney, either by pedicle occlusion or nephrectomy, caused an immediate rise in solution excretion from the contralateral kidney, but Cin remained unchanged. Unflushed severely damaged kidneys showed no compensatory response to unilateral nephrectomy, whereas kidneys flushed with PBS50 exhibited increases in solute excretion similar to those seen in healthy non-ischaemic kidneys.