Abstract: It have examined the effects of intravenous (iv) infusion or intraventricular(icv)injection of brain natriuretic peptide(BNP)on the brain water,sodium and potassium contents in rat ischemic brain edema produced by right meddle cerebral artery(MCA)occlusion.In the group treated with iv infusion of 0.9% NaCl,the water and sodium contents in the right cerebral cortex(ischemic region)increased significantly compared with that in the left(nonischemic region).In the group treated with iv infusion of BNP,however,there is no significant difference between left and right in brain water and sodium contents. No effect of iv BNP infusion on the decrease of potassium content was observed.Although the water content in the right cerebralcortex(ischemic region)increased significantly compared with that in the left(non-ischemic region)in both of the groups treated with NaCl and BNP by icv injection,a significant difference in brain water content in the right cerebral cortex was observed.between NS and BNP groups.Icv injection of BNP inhibited significantly the increase of sodium content in the right ischemic region.The decrease of potassium content in the right ischemic region was not observed in the group of icv infection of BNP.The results show that BNP given by iv or icv reduced brain edema and inhibited the increase of sodium content in ischemic region.Icv injection of BNP inhibited the decrease of potassium content in ischemic region,but iv infusion of BNP didn't.It is convinced that BNP is involved in the regulation of systemic fluid and electrolyte balance in the peripheral and central nervous system.The effects of BNP on brain potassium in peripheral and central nervous system may be mediated by different mechanism.

Key words: brain natriuretic peptide, ischemic brain edema, rat