Bumetanide Can Inhibit Ischemic Cerebral Edema By Downgreduating AQP4 Through Inhibiting NKCC1 Expression

Objective: Observing the connection between AQP4,NKCC1 and cerebral edema after ischemic injury,and the changes after injecting bumetanide in rats. Exploring the internal relations between AQP4 and NKCC1 in ischemic cerebral edema.Methods: Pick 104 healthy male SD rats which weigh 300~350g. Randomly divided them into three groups: sham group, model group, bumetanide group. Model group and bumetanide group are maken ischemic/reperfusion, taking a middle cerebral artery occlusion(MCAO) /reperfusion model, and injecting bumetanide 30mg/Kg(bumetanide DMSO solution,concentration:25mg/Kg) before occlusion in bumetanide group. Sham group is not given middle cerebral occlusion. All groups were randomly selected to collect Zea longa 5scores to evaluate the model wether succed. At 0h,3h.6h,24 h,3d and 7d after the surgery, each time point,4 rats were tested cerebral edema by wet/dry weight ratio(WD), 4 rats were put to death,brain tissue of each were abtained to calculate the expression level of NKCCI and AQP4.Results: Under light microscope in HE staining slide, we have not found abnormal changes of sham group. The bumetanide group have better than model group in neuronal necrosis, brain edema and organization structure disorders. The results of wet/dry weight ratio: the cerebral edema was increased after middle cerebral arteryedema,the gray values appeared on 3rd day both in model group and bumetanide group. Compared bumetanide group with model group, at 0h, 3rd hour,the cerebral edema do not have increased obviously, at 6th hour, 24 th hour, 3rd day,7th day, the cerebral edema have statistical inceased. The results of immunohistochemical :the gray ratio expression of NKCC1 and AQP4 both appeard on 3rd day, on7 th day the expression has a little decreased. Compared sham group with model group, at 0h and 3rd hour have not statistical meanings, but at 6th hour, 24 th hour, 3rd day, 7th day the expression of NKCC1 and AQP4 of model group have statistical increased. Compared model group with bumetanide group, at 0h, the expression of NKCC1 and AQP4 have no obvious increased, at 3rd hour,6th hour,24 th hour,3rd day,7th day, the expression of NKCC1 and AQP4 of bumetanide group have statistical decreased than model group.Conclusion: 1. After middle cerebral artery occlusion, the cerebral edema has internal connection with the expression of NKCC1 and AQP4. 2. The mechanism of bumetanide decrease ischemic cerebral edema through inhibit NKCC1 that may downgreduate the expression of AQP4.