Abstract：Objective To examine the changes of nitric oxide and oxygen free radical in the kidneys of neonatal rats with lung injury induced by prolonged hyperoxia in order to study the induction of renal damage by prolonged hyperoxic exposure. Methods Full-term newborn rats were continuously exposed to oxygen (90%±5% O 2,n=140) or room air (21% O 2,n=88) after birth. Dynamic changes of superoxide dismutase (SOD) activity and content of malondialdehyde (MDA) and nitric oxide (NO) in the lung and kidney were monitered by spectrophotometer on days 1, 3, 7, 14 and 21 in the Hyperoxia and Control group. Results In the Hyperoxia group, SOD activity in lungs began to increase on the 3rd day, and significantly higher than that of controls on the 7th day (214±19 KNU/g vs 186±19 KNU/g, P< 0.01), 14th day (220±15 KNU/g vs 197±21 KNU/g, P< 0.05) and 21th day (251±15 KNU/g vs 195±8 KNU/g, P< 0.01). The MDA level in the lungs increased on the 3rd day ( 28.1± 2.0 μmol/g vs 21.1± 1.3 μmol/g, P< 0.05) and reached a peak on the 7th day ( 30.8± 4.2 μmol/g vs 19.9± 2.2 μmol/g, P< 0.01), then decreased but still remained higher than controls on the 14th day ( 26.3± 3.8 μmol/g vs 22.6± 2.3 μmol/g, P< 0.05). The NO level began to increase and was higher than controls on the 7th day (99±8 μmol/g vs 89±8 μmol/g, P< 0.05), and 14th day (128±34 μmol/g vs 93±17 μmol/g, P< 0.05) and 21st day (171±34 μmol/g vs 106±25 μmol/g, P< 0.01). In the kidney, although there was little difference in SOD activities between two groups, the levels of MDA and NO increased on the 14th day ( 24.1± 5.0 μmol/g vs 16.0± 1.9 μmol/g, P< 0.01; 286±71 μmol/g vs 222±45 μmol/g, P< 0.05), continuously to 21st day ( 16.5± 2.2 μmol/g vs 13.0± 2.7 μmol/g, P< 0.05; 298±65 μmol/g vs 204±49 μmol/g, P< 0.01). These changes appeared later than in the lungs. Conclusions Renal damage can be induced by prolonged hyperoxia exposure and be developed behind lung injury in neonatal rats.
LIU Xue-Yan,WU Jie,XUE Xin-Dong. Changes of nitric oxide and oxygen free radical in the kidney of neonatal rats with prolonged hyperoxic lung injury[J]. CJCP, 2005, 7(1): 71-74.
