The Experssion Of Aquaporin 2 In Acute Kidney Injury Duiring Multiple Organ Dysfunction Syndrome

Objective : Critically ill patients, especially those with severe infection or poisoned or ischemia-reperfusion injury, was prone to multiple organ dysfunction syndrome(MODS), while kidney is one of the organs most frequently affected. These patients with MODS and kidney injury, due to severe water and electrolyte acid-base unbalance, mortality was significantly increased. AQP2 express in the kidney and regulate the permeability of the collecting duct water by vasopressin. AQP2 played an important role in renal water metabolism. AQPs is the structural basis for water and urea membrane active transport. It provides a new target for monitoring dynamic change of renal function and early intervention and treatment of renal injury. AQP2 abnormal expression may lead to a variety of congenital or acquired kidney disease. Renal Na~+-K~+-ATPase is known as the sodium potassium pump, inlaid in the renal tubular cell membrane lipid bilayer. Na~+-K~+-ATPase not only transport sodium and potassium ion, it can also release the decomposition of ATP and active transport sodium and potassium. Na~+-K~+-ATPase’s function was positively correlated with the severity and recovery of disease, and prior to the improvement of disease. It is important to determine the condition and prognosis of the disease.Through this experiment, we investigate the characteristics of expression of AQP2 and Na~+-K~+-ATPase in MODS ratsand try to find the possible mechanism of renal injury from the molecular level,inflammatory and energy metabolism.Materials and methods: 1. We make multiple organ dysfunction animal model by intraperitoneal injection of lipopolysaccharide 5mg/kg or paraquat 20mg/kg gavage, MODS animal model were give or not give lysine aspirin, and the control group only false operation treatment. 2. Immunohistochemical staining to determine kidney AQP2 protein expression level. 3. RT-PCR to determination of kidney AQP2 m RNA expression level. 4. Cut renal medullary tissue, HE staining to examine renal morphological changes. 5. Tubular epithelial cell Na~+-K~+-ATPase determination with Na~+-K~+-ATPase kit. 6. Determination the expression of IL-1,IL-10,TNF-ɑ in paraquat rats peripheral blood by ELSIA and apoptosis of peripheral blood lymphocyte ratio by flow cytometry.Results: 1. Compare to control group, the amount of urine decreased and creatinine, blood urea nitrogen level gradually increased in the LPS rats. In paraquat group, the amount of urine was normal while the creatinine, blood urea nitrogen level gradually increased. 2. In LPS group, rat kidney biopsy showed obvious swelling of renal tubular epithelial and glomerular cells, tubular lumen becomes smaller, renal tubular cells partial necrosis. In paraquat group, rat kidney biopsy showed swelling significantly, but rarely cell necrosis.3. AQP2 m RNA expression of rats renal tubular epithelial cells increased in LPS group at 6h, but then decreased rapidly to a minimum at 48 h, and then gradually increased. AQP2 m RNA expression of rats renal tubular epithelial cells decreased in paraquat group, but lysine aspirin can reduce this change. 4. AQP2 protein expression in renal tubular epithelial cells of rats in the experiment LPS group appears to reduce after 12 hours, and after 48 hours the kidney AQP2 protein expression decreased most significantly, then gradually increase. AQP2 protein expression of rats renal tubular epithelial cells decreased in paraquat group, but lysine aspirin can reduce this change. 5. The content of Na~+-K~+-ATPase show no significant difference in different group. But the activity of Na~+-K~+-ATPase was significantly reduced after the model is successful in LPS and paraquat group, then gradually increased, but still lower than the control group. 6. Lymphocyte apoptosis ratio of paraquat poisoned rats increased significantly, the expression of TNF-ɑ、IL-1、IL-10 increased significantly. Lysine aspirin can inhibit the apoptosis of lymphocyte and the expression of TNF-ɑ and IL-1, but promote the expression of IL-10 increased.Conclusion: 1. In LPS induced multiple organ dysfunction syndrome rats, the increase of blood urea nitrogen and creatinine, the decrease of APQ2 expression was caused by the swelling, dysfunction or apoptosis of renal tubular epithelial cells. 2. In multiple organ dysfunction syndrome caused by LPSrats, the amount of urine was negatively correlated with and the expression of AQP2 during the renal restore stage. AQP2 is the structural basis for renal reabsorption of functional and Na~+-K~+-ATPase reflect the energymetabolism of kidney.The renal function gradually improved unless the expression of AQP2 protein and energy metabolism of kidney near normal level. 3. Lysine aspirin can significantly reduce the acute renal injury and inflammatory reaction caused by LPS. 4. Paraquat poisoning can cause systemic inflammatory response and multiple organ dysfunction. But these symptoms caused by paraquat is delayed, suggesting that MODS is caused by excessive inflammatory reaction, but not toxic paraquat directly. 5. Whether the MODS is caused by LPS or paraquat, lysine aspirin can significantly reduce the acute renal injury by suppressing inflammatory reaction.