Ischaemic preconditioning protects the rat kidney from reperfusion injury

Objective. To examine the possible role of ischaemic preconditioning (IPC), an adaptive pathophysiological phenomenon that increases tolerance to ischaemia-reperfusion (I-R) injury, in renal protection when rats are presented with an I-R challenge. Materials and methods. Female Wistar rats (n = 36) were divided randomly into four groups: (A) sham-operated controls; (B) IPC only; (C renal ischaemia (RI) only: and (D) IPC + RI. The left kidney in groups B and D was preconditioned with four cycles of renal artery occlusion lasting 4 min, each occlusion separated by 11 min of reperfusion. The ischaemic insult, applied in groups C and D, comprised 40 min of sustained left renal artery occlusion. In Group D, the IPC cycle was completed 5 min before the start of the ischaemic insult. Differential left renal function was calculated by ^99mTc-labelled dimercaptosuccinic acid scintigraphy at 0, 2 and 9 days after treatment, and expressed as a percentage of the total renal uptake. Results. The mean (SEM) maximum decrease in left renal funtion, to 14.5 (4.3)% of the total, occurred on day 2 in Group C. The equivalent value in Group D showed relative preservation of function, at 36.0 (3.5)% (P = 0.001 compared with Group C). The mean left renal function improved by day 9, to 39.6 (6.7)% (Group C and 48.6 (1.5)% (Group D). The mean left renal function in Group B (50.5-53.9%) did not differ from that in controls (49.4-51.4%). Conclusion. An IPC regimen applied 5 min before RI in the rat significantly protects it from the functional impairment associated with ischaemia and reperfusion.