Expression of nitric oxide synthase system in fetal rat kidney after acute ischemia(hypoxia)/reperfusion

Objective To investigate the relationship of nitric oxide with nitric oxide synthase system in fetal rat kidney and the mechanism of renal injury after acute intrauterine ischemia(hypoxia)/reperfusion ischemia(hypoxia)/reperfusion. Methods Wistar rats of 21 gestational days were selected and divided into seven groups according to the different ischemia(hypoxia)/reperfusion time. The level of nitric oxide and the expression of nitric oxide synthase system were detected by biochemistry, immunohistochemistry and RT PCR. Results The NO level was decreased gradually with extension of ischemia, which was significantly different from sham group ( P 0.01). During reperfusion, the level of NO decreased initially and then increased, reached its peak value at 6hrs after reperfusion and stayed at a high level at 24 hrs ( P 0.05). eNOS and iNOS were all expressed in proximal tubules in sham operation group. The mRNA contents and the activity of eNOS were significantly decreased gradually along with the longer period after ischemia/reperfusion (the intensity of eNOS increased) comparing with sham group ( P 0.01). The trend of iNOS was opposite to that of eNOS especially after reperfusion 6 hours ( P 0.01 and P 0.05 respectively). Conclusions The NO level showed biphasic change in fetal rat kidney after acute intrauterine ischemia(hypoxia)/reperfusion, which was related with renal injury. It might be the consequence of the NOS.