To explore the changes of nitric oxide and its role in renal injury in obese rats. MethodsSixteen healthy male Wistar rats were randomly divided into the control(n=8) and obese group(n=8) which were respectively given an ordinary diet and a high fat diet. After 20 weeks, all rats were killed. The Lee index, left renal index, the content of cholesterol total(TCH), triglyceride(TG), low density lipoprotein cholesterol(LDLC) , high density lipoprotein cholesterol(HDLC) and urine protein quantitation in 24 hours(UPE) and creatinine clearance(Ccr) were detected. Nitric oxide (NO) content in blood , renal tissue and urinary nitrite+nitrate excretion (UNOxV) were acquired by a nitrate disoxidation method. Histomorphology of kidneys was examined by an optical microscope, and the glomerulum section area was determined by image analysator. ResultsIn the obese group, the index of Lee, left renal index, cholesterol total(TCH), triglyceride (TG), low density lipoprotein cholesterol(LDLC), urine protein quantitation in 24 hours and creatinine clearance(Ccr) were significantly higher (P<0.01), while high density lipoprotein cholesterol(HDLC), nitric oxide(NO) content in blood, renal tissue and urinary nitrite+nitrate excretion (UNOxV) were lower(P<0.01). In the obese group, mesangial cell proliferation, Bowman′s space proprius adhesion, interstitial arteriole endothelial hyperplasia, hyalinosis and glomerular average section area were obviously increased (P<0.01). Relative analysis demonstrated that the NO contents of the serum and renal tissue were negatively correlated with TG, TCH, LDLC, UPE, Ccr and glomerulum section area(r=-0.869?4,-0.788?1; -0.795?4,-0.783?5; -0.918?2,-0.873?0; -0.894?0, -0.903?5; -0.612?2, -0.553?5; -0.641?1, -0.599?6), while positively correlated with HDLC and UNOxV(r=0.934?9,0.930?7; 0.855?7,0.822?1). ConclusionThere were evident functional disturbances of blood vessel endothelium and capillary vessel endothelium and renal damage in the obese group. The former is relevant to the conspicuous lipid metabolism disorder, and the latter is relevant to insufficient NO synthesis. As a noninvasive detection indicator, UNOxV can indirectly reflect NO synthesis in obese rats.