A Preliminary Research On Safe Duration Limit Of Secondary Warm Ischemia In Rat’s Kidney

Experiment 1 The research on safe duration limit of single warm ischemia in rat kidneyObjective:To establish renal single ischemia reperfusion models on rats and make sure the safe duration limit kidney to clamp left renal pedicle.Methods:36 Sprague-Dawley rats (male and female) were randomly separated into two groups:control group with 6 rats and warm ischemia group with 30 rats. Warm ischemia group were divided into five subgroups by the different warm ischemia time (WI 15min, WI 30min, WI 45min, WI 60min, WI 75min), there are 6 rats in each subgroup. In control group, the right kidneys were removed only. In warm ischemia group, right kidneys were removed and the left renal pedicles were clamped for different warm ischemia time (WI 15min, WI 30mm, WI 45min, WI 60min, WI 75min), then persistent reperfusion 24 hours. After 24 hours reperfusion, all of the rats were killed. Blood samples were collected to determine serum creatmine (SCr) and urea nitrogen (BUN) concentrations so that we can definite the degree with renal function injury. At the same time, kidneys were taken out from Retroperitoneum to be evaluated by light microscopy.Results:Sc^ BUN level of WI 30min、WI 15min were similar to that of the control group(P>0.05). However, there was significant difference between sham group and other 3 groups whose left renal pedicles were clamped more than 30min(P<0.05). WI 45min、WI 60min、WI 75min demonstrated renal dysfunction and the 2 indexes of them were increased obviously. Values of Scr and BUN of WI 45min、WI 60min、 WI 75min were compared in pairs(P<0.05), the longer warm ischemia time resulted in higher level of the 2 indexes. Findings(vacuolation of renal tubular epithelial cells、casts) of renal morphology showed that groups of WI 45min、WI 60min、WI 75min had severer tubular performance than that of WI 30min、WI 15min and the sham group.Conclusion:1. The safe duration time of single warm ischemia in rat’s kidney was 30min.2. When the single warm ischemia time reached 45min, the damage in renal function and tissues was observed.3. When the single warm ischemia time was over 45min, as time goes on, the damage of renal function and tissues would be worse and worse. them were increased obviously. Values of Scr and BUN of WI 45min、WI 60min、 WI 75min were compared in pairs(P<0.05), the longer warm ischemia time resulted in higher level of the 2 indexes. Findings(vacuolation of renal tubular epithelial cells、casts) of renal morphology showed that groups of WI 45min、WI 60min、WI 75min had severer tubular performance than that of WI 30min、WI 15min and the sham group.Conclusion:1. The safe duration time of single warm ischemia in rat’s kidney was 30min.2. When the single warm ischemia time reached 45min, the damage in renal function and tissues was observed.3. When the single warm ischemia time was over 45min, as time goes on, the damage of renal function and tissues would be worse and worse.Experiment 2 The research on safe duration limit of secondary warm ischemia in rat’s kidneyObjective:To establish the renal secondary warm ischemia reperfusion models on rats and investigate the safe duration limit of renal secondary ischemia.Methods:64 Sprague-Dawley rats (male and female) were randomly separated into 3 groups:control group with 8 rats, single warm ischemia 30min group with 8 rats, secondary warm ischemia group with 48 rats. These 48 rats were divided into 6 subgroup by the different secondary ischemia time (SSWI 5min, SWI 10min, SWI 15min, SWI 20min, SWI 25min, SWI 30min)and each subgroup contained 8 rats. In control group, the right kidneys were removed only. In single warm ischemia group right kidneys were removed and the left renal pedicles were clamped for 30min. All rats in secondary warm ischemia group were resected and occluded the left renal pedicle 30min followed by a 10 minuts reperusion, then clamped the renal pedicle 5min、10min、15min、20min、25min、30min. After 24 hours reperfusion, we collected blood samples from inferior vena cava to detect Scr and BUN. To take half of the left kidney to do HE-staining and evaluated renal injury through Pallets nephric tubule score. The expression of Bcl-2 and Bax was assayed by immunohistochemical staining. The rest kidney was made into homogenate for dectecting SOD and MDA.Results:Scr、BUN level of SWI 30min、SWI 5min、SWI 10min、SWI15min were similar to that of the control group(P>0.05), compared with SWI 20min group, and the difference was statistically significant (P< 0.05).Compared to sham group,the scores of renal tubular injury in residual groups increased clearly(P<0.05).Compared to sham group, the activity of SOD in SWI 20min group、SWI 25min group、SWI 30min group was significantly low(P<0.05). There was no significantly difference among sham group and the residual groups.The values of MDA in single WI 30min group were higher than those in sham group(P<0.05) and SWI 5min group(P<0.05), however, there was no statistically significance(P>0.05), when compared sham group with SWI 5min group and SWI 10min group. MDA in SWI 15min group was compared with single WI 30min group、SWI5 min group、SWI10 min group in pairs and higher than those of other 3 groups(P<0.05).Compared to sham group, the rate of Bcl-2/Bax in SWI 20min group、SWI 25min group、SWI 30min group decrased (P <0.05). There was no significantly difference among sham group and the residual groups(P>0.05).Conclusions:1. After the first 30min warm ischemia time,the secondary safe duration was 15min.2. When the secondary warm ischemia time was over 20min, the renal function and tissues in rats would be damaged seriously.