| Objective: Kidney, as a hypertransfusion organ, is extremely sensitive to ischemia and the ischemical reperfusion injury(IRI) often comes along with it. It is known that acute renal failure(ARF) is significantly associated with the renal IRI but the mechanism of renal IRI formation in pathology and physiology is very complex. Most recent study on renal IRI in pathology and physiology is primarily focused on the aspects of the apoptosis and necrosis of renal tubular epithelial cell,free radical injury,calcium overload,the obstacles of energy metabolism,adhesion molecule,cell factor and so on.There is little work reported to emphasize the important role that the renal Aquaporin-2(AQP2) plays in this respect. The main objective of this study, therefore, is to build a renal IRI model of rats and to investigate the relationship between the change of AQP2 and the renal function based on the model. The formation mechanism of renal IRI and ARF is explored the correlation between the diuresis urorrhagia and AQP2 expression after ARF,and provide the theoretical background for clinical service.Methods: 50 healthy adult male SD rats are collected. They are selected randomly to partition into two groups, one is for experimental study and another is used as a control group. A model is built based on the data obtained from the experimental study where the abdominal surgery is performed in order to separate the right kidney with no damage artery clip. The renal blood perfusion is then restored after 45 minutes. In the control group, however, only free right renal pedicle for clip is closed without using the clip and the abdomen is closed after 45 minutes. In the experimental group, the urine, blood and the left and right side of kidney are collected on day-1, day-3, day-5 and day-7 after surgery with 10 rats in each group. The rats belonging to the control group are put to death on day-1 and used as the specimens. The 24 h urine quantity and its specific gravity are measured using the specimens. The change of the creatinine and urea nitrogen is also observed through the blood serum which is separated from the whole blood. The kidney is used to detect the HE, immunohistochemistry and QRT – PCR. By means of the HE staining technology, the renal pathology variation is discovered. The expression level of AQP2 and its distribution is obtained using the immunohistochemical method. Finally, the expression level of AQP2 m RNA in the kidney of rats are measured by using a real-time fluorescent quantitative PCR.Results:1 Urine changes:(1) The urine changes for 24 hour interval: The urine collected in a 24 h interval is observed to vary from day to day for the rats with Ischemia-reperfusion. The 24 hour urine from the model rats appears to be exceptionally high on day-1 after surgery. It reaches a highest level on day-3 and then decreases continuously until day-7 when the urine returns to normal. Comparatively, the sham-operated rats have been found to have lower level of the 24 h urine on day-1 but higher on day-7. The changes observed in urine output in each group is statistically significant(P<0.05).(2) The change of specific gravity of the urine: The specific gravity of the urine from the rats with ischemia-reperfusion is observed to be lower on day-1 after surgery and continuously decreased until day-3 when it reaches an lowest level. The urine then increases to normal on day-7. It is found that the sham-operated rats have a higher specific gravity compared to that in the experimental group on day-7 and day 1after surgery. The difference between the data on day-1 and day- 7 is statistically significant(P<0.05).2 The indicators of renal function: A continuously increased urea nitrogen and the creatinine expression contained in the kidney of the rats in the ischemia-reperfusion model group have been discovered. The urea nitrogen and creatinine reach the peak level on day-3 after surgery. They are then decreased gradually until on day-7 when they return to normal. The difference of urea nitrogen measured on day-1 and day-7 after surgery is not significant in statistics(P>0.05). The difference between the Urea nitrogen on day-7 after surgery and that on day-1 in the sham group is not significant in statistics(P>0.05). The difference between the creatinine on day-7 after surgery and that on day-1 obtained in the sham group is not significant in statistics(P>0.05).3 Pathology observation: The obvious renal tubule degeneration, cavitation and necrosis have been discovered when the HE dyeing is used for the rats in schemia-reperfusion.4 Immunohistochemical: the difference between the expression of AQP2 on left and right side of the kidney in sham group has been found not statistically significant(P>0.05). It has been discovered that for the bilateral renal ischemia-reperfusion rat model, the AQ2 expression is statistically significant(P<0.05) at different time instant after surgery. The AQP2 expression in the left kidney of the model rats is observed to vary from time to time. The AQP2 expression on day-1 after surgery is exceptional high and it continuously elevate until on day-3 when it reaches the highest level. It then gradually decrease and returns to normal on day- 7.5 QRT- PCR: The results are observed to be the same with the immunohistochemical. AQP2 m RNA of the rat kidney in the sham group has no significant difference(P>0.05). The AQP2 m RNA expression in both kidneys of rats in model group is significantly different in statistics(P<0.05). The AQP2 m RNA in model group for the left kidney starts to increase on day-1 after surgery and reaches the highest level on day-3. It then goes down gradually to reaches the stable and normal level on day- 7.Conclusions:1 The rats used as the model of ischemia-reperfusion have obvious injury in renal tubular. HE staining shows that there is a significant renal tubular degeneration, vacuoles and necrosis. It indicates that the renal function changes accordingly as the time of ischemia-reperfusion goes on. All of the above observation suggests that the ischemia-reperfusion injury is one of the main causes of acute tubular necrosis and renal failure.2 Ischemical reperfusion injury(IRI) brings about the decrease of AQP2 expression level of rats. The re-absorption of water thus becomes much more difficult. This could be one of the main reasons which can be used to explain why the rats have the increased urine and decreased urine specific gravity after acute renal failure.3 The fact that the change of AQP2 expression of rats is always associated with the IRI reveals that the AQP2 level could be used as an important indicator of the renal function of rats. The AQP2 actually plays an important role in pathology and physiology process of the renal ishemical reperfusion injury. |
PDF Full Text Request