New model of renal warm ischaemia-reperfusion injury for comparative functional, morphological and pathophysiological studies

Background Renal warm ischaemia-reperfusion injury is pertinent to vascular and transplant surgery. While established models provide functional and mo rphological data the authors wanted to be able to correlate this with the u nderlying pathophysiology at any chosen time point, thus allowing future in terventional effects on reperfusion injury to be evaluated. Methods In a rodent model bilateral renal warm ischaemia (15-60 min) and th en reperfusion (20 or 80 min) before nephrectomy allowed for analysis of ea rly reperfusion pathophysiology. The remaining kidney provided functional d ata (glomerular filtration rate (GFR)) at days 2 and 7 before nephrectomy f ur late analysis and morphology using a new grading system. Results Acceptable survival rate (ten of 12 animals) was seen with up to 45 min of warm ischaemia. Renal function was impaired at day 2 following 30-6 0 min of warm ischaemia (P < 0.01) and day 7 in the 45- and 60-min groups ( P < 0.05 and P < 0.01 respectively). Strong correlation existed between dur ation of ischaemia and GFR at day 2 (r(2) = 0.88) and day 7 (r(2) = 0.95). Histological damage in the cortical tubules was evident in the 45- and 60-m in groups (P < 0.01). Conclusion This new model allowed comparative functional, morphological and pathophysiological studies while minimizing the number of animals required . Overall 45 min of warm ischaemia gave significant, recoverable injury and is recommended for investigating renal reperfusion injury.