The Protective Role Of Mitochondrial Apoptosis Pathway In Rat Renal Ischemic Postconditioning

Objective:To observe the variance of mitochondrial ATP-Sensitive K+ Channels and the effect of the mitochondrial ATP-Sensitive K+ Channels to Mitochondrial Permeability transition Pore in renal tubular epithelial cell ,To investigate the protective role of mitochondrial apoptosis pathway in rat renal ischemic postconditioning.Methods:Thirty-five male SD rats weighing 250-280g were randomly allocated into 5 groups (n=7 each): groupⅠsham operation (S); groupⅡischemia-reperfusion I/R; groupⅢischemic postconditioning(IPo); groupⅣI/R+5-HD; groupⅤIPo+5-HD. The rats were anesthetized with intraperitoneal chloral hydrate 300 mg·kg-1. Bilateral kidneys were exposed through midline incision and bilateral renal pedicels were occluded 45 min with atraumatic mini-clamp then unclamped for 6 h. The kidneys turned kermesinus. In group S the kidneys were exposed but their pedicles were not clamped. In group IPo, 45 min ischemia was followed by three 10 s episodes of ischemia and 10 s intervals for reperfusion. In group I/R+5-HD, 5-HD(10mg·kg-10) was given intraperitoneal at 30min before ischemia, the other operation same to group I/R . In group IPo+5-HD, 5-HD(10mg·kg-10) was given intraperitoneal at 30min before ischemia,the other operation same to group IPo.In group S, Same cubage 0.9% brine was given intraperitoneal at the same time with group IPo+5-HD. The animals were killed at 6h of reperfusion.Blood samples were taken from heart for determination of serum creatinine(Cr), urea nitrogen(BUN) . Detecting the fluorescence intensity of mitochondrial permeability transition pore, intraceller ca2+,Mitochondrial Membrane Potential,intraceller ROS by laser confocal microscope imaging of intact cells loaded with related reagent. ImageJ software image analyse.The apoptosis in the nephridial tissue was assessed using TUNEL and apoptotic index(AI) was calculated.Results:The Cr and BUN concentrations: Compared with group S, group I/R,IPo,I/R+5-HD and IPo+5-HD increased totally(P<0.05),Compared with group I/R,Group IPo decreased(P<0.05),Compared with group IPo,I/R+5-HD and IPo+5-HD increased totally(P<0.05),Group I/R,/R+5-HD and IPo+5-HD had no statistic meaning(p>0.05).The fluorescence intensity of intraceller ca2+, the intraceller ROS and AI: Compared with group S, group I/R,IPo,I/R+5-HD and IPo+5-HD increased totally(P<0.05),Compared with group I/R,Group IPo decreased(P<0.05), Compared with group IPo,I/R+5-HD and IPo+5-HD increased totally(P<0.05), Group I/R,I/R+5-HD and IPo+5-HD had no statistic meaning(p>0.05).The fluorescence intensity of Mitochondria and Mitochondrial Membrane Potential:Compared with group S, group I/R,IPo,I/R+5-HD and IPo+5-HD were decreased totally(P<0.05),Compared with group I/R, Group IPo was increased(P<0.05), Compared with group IPo , groups I/R+5-HD and IPo+5-HD decreased totally(P<0.05),group I/R,I/R+5-HD and IPo+5-HD had no statistic meaning(p>0.05).Conclusion: Ischemic-postcondation can activate mitochondrial ATP-sensitive potassium channel and maintain mitochondrial membrane potential, relieve calcium overload of the cell, reduce intracellular ROS production, inhibit the opening of mitochondrial permeability transition pore, lower renal tubular epithelial apoptosis and improve renal function. Overall, the mitochondrial apoptosis regulatory pathway plays a crucial role in the protective effect of renal IPo during renal ischemia-reperfusion injury.