Objective: To compare the effect of ischaemic preconditioning (Ipre) vs. ischaemic postconditioning (Ipost) on renal ischaemia/reperfusion (I/R) injury in rats.
Materials and methods: In all, 120 male Sprague-Dawley rats were classified into four groups of 30 rats each, designated sham, control, Ipre and Ipost. Renal function, including serum creatinine, blood urea nitrogen (BUN), creatinine clearance (CrCl), fractional Na excretion (FENa) and renal histopathology were measured at 2, 24 and 48 h after ischaemia. Markers of lipid peroxidation (malondialdehyde, MDA), superoxide dismutase (SOD) and reduced glutathione (GSH) were measured in kidney tissues during the same intervals.
Results: Ipre caused a significant improvement in renal function, as indicated by a significant decrease in serum creatinine, BUN and FENa, with a significant increase in CrCl. However, Ipost caused no significant improvement in renal function. Morphologically Ipre caused a marked significant improvement in the renal tubular damage score compared to Ipost. Also, Ipre caused a significant decrease in MDA, and significant increase in GSH and SOD when compared to Ipost.
Conclusion: Ipre is more potent than Ipost for improving the renal injury induced by I/R. Ipre caused a marked improvement in renal function and morphology, while Ipost caused a minimal improvement in morphology only. Moreover, Ipre caused a marked and significant reduction in oxidative stress in kidney tissues, while Ipost caused a minimal reduction.
Keywords: BUN, blood urea nitrogen; CrCl, creatinine clearance; FENa, fractional Na excretion; GSH, reduced glutathione; H&E, haematoxylin and eosin; I/R, ischaemia/reperfusion; Ipost, ischaemic postconditioning; Ipre, ischaemic preconditioning; Ischaemia/reperfusion; MDA, malondialdehyde; OSOM, outer stripe of the outer medulla; Oxidative stress; Postconditioning; Preconditioning; ROS, reactive oxygen species; Rat; SOD, superoxide dismutase.