Effect of preoxygenation on the expression of iNOS in brain induced by hypoxia / reoxygenation in rats / 中华麻醉学杂志

ABSTRACT

Objective To determine the expression of inducible nitric oxide synthase (iNOS) in brain after cerebral hypoxia / reoxygenation and the effects of preoxygenation with different concentrations of oxygen in rats.Methods Seventy-two male Wistar rats weighing 250-300 g were randomly divided into 4 groups group Ⅰ, Ⅱ ,Ⅲ ,and Ⅳ . Each group was further divided into 3 subgroups a, b, c. Group Ⅰ a, Ⅱ a, Ⅲ a and Ⅳa were preoxygenated with 21 % O2 (Ⅰa), 50 % O2 (Ⅱ a) , 75 % O2 (Ⅲa) and 95 % O2 (Ⅳ a) for 30 min. GroupⅠ b-Ⅳb were subjected to hypoxia (5 % O2 ) for 20 min after preoxygenation. Group Ⅰc-Ⅳc were reoxygenation (98 % O2) for 20 min after preoxygenation and hypoxia. The animals were sacrificed 48 h after the experiment. Brains were immediately removed for microscopic examination and determination of iNOS expression in brain using immuno-histochemistry technique. Results The number of iNOS positive cells was significantly greater in hypoxia groups than that in preoxygenation groups ( P