Changes of Nitric Oxide Synthase Activity in Penumbral and Core Area during Focal Cerebral Ischemia and Reperfusion in Rats

Objecivee: To study the changes of nitric oxide synthase (NOS) activity in penumbral and core area during focal cerebral ischemia and reperfusion, and to explore the therapeutic window of focal cerebral ischemia. Methods:The middle cerebral artery of rats was occluded for 15, 30,60,90 and 120 min by an inraluminal filament respectively,and recirculation was instituted for 24 h. The changes of NOS activity in ischemic core area(parietal cortex and caudoputamen) and penumbral area ( frontal cortex)were examined after focal cerebral ischemla and reperfusion using NADPH-d histochemistry, technique. Results. The NOS activity of the ischemic penumbral area peaked at 60 min while the ischemic core area peaked at 30 min then declined at 90-120 rain sharply. Conclusion: NOS takes part in cerebral ischemic damage during focal cerebral ischemia and reperfusion. The NOS activity of the ischemic penmnbral area is different from the ischemic core area. The peak time of the penumbral area is delayed comparing with the core area. The data suggest that the best time to apply NOS inhibitor is within 30 min in ischemic core area, and 60 rain in penumbral area.