Effect Of Controlled Severe Hypotension With Time On Expression Of COX-2 And HSP70 In Brain Hippocampus CA1 Subregion And Survival Rate In The Rats

Objective:Controlled hypotension has been generally used in special anaesthetic practice.It is generally accepted that controlled hypotension is safe when mean arterial pressure(MAP) is large than 50mmhg in normotension patients.Many studies have different argument on effect of hypotension on cerebral tissue,and it is not very clear today. our study produce hypotension induced by sodium nitroprusside(SNP) and esmolo(ESM) in the rats,to explore change of survival rate,neurologic and behavioral assessment and brain tissue morphological after different extent lasting hypotension,At the same time,through the exploration of controlled drugs with severe hypotension caused by cerebral ischemia when the blood pressure threshold and the limits,to study the extent of severe low blood pressure and duration of the injury and the brain tissue and the degree of relevance,guide for the prevention and treatment of clinical severe low blood pressure caused by cerebral ischemia Further research.Methods:46 SD rats were randomly divded into 7 groups:A group(operation control),B1 group(level of MAP50mmhg controlled for 30 minutes),B2 group(level of MAP50mmhg controlled for 60 minutes) C1 group(level of MAP30mmhg controlled for 30 mintues),C2 group(level of MAP30mmhg controlled for 60 mintues),D1group(level of MAP25mmhg controlled for 30 mintues),D2group(level of MAP25mmhg controlled for 60 mintues) the combination of sodium nitroprusside(SNP)and esmolol induce hypotension and retain Corresponding times hypotension,each group contain 6 SD rat. Recording vital sign of rats and doing blood gas analysis during controlled hytrolled hypotension,and observing survival rate,neurologic and behavioral assessment and brain tissue morphological change after hypotension.Result:1.One day after hypotension,survival rate in group A,B1,B2 were all 100%,survival rate in group C1,C2 and D1 were respectively:67%, 38%,38%.there were much difference(P＜0.05).2.No pathology sign were observed in 1 day after hypotension in seven group.But neurologic and behavioral assessment in group C1,Dland C2 had much difference.(P＜0.05)3.HE staining:there were no significant changes of cell apoptosis and death in group A,B1,and B2.there are normal cells mainly.(P＞0.05) But group C1,D1 and C2 had much difference.(P＜0.05)4.HSP70 immunohistochemical staining:there were negative expression of hsp70 in group A,B1andB2(P＞0.05).there were positive expression of hsp70 in group roup C1,D1 and C2(P＜0.05)5.Cox-2 immunohistochemical staining:there were negative expression of cox-2 in group A,B1,B2(P＞0.05).there were positive expression of cox-2 in group roup C1,D1 and C2(P＜0.05)Conclusion:1.There were no pathology sign and abnormal neuroethology after 30 and 60 minutes hypotension of map50mmhg induced by SNP and ESM,and no cell apoptosis and death in brain hippocampus section.there were negative expression of hsp70 and cox-2 in group MAP50 mmhg.2.There were much pathology sign and abnormal neuroethology after 30 minutes hypotension of map30mmhg induced by SNP and ESM,hsp70 and cox-2 positive expression,and some changes in brain hippocampus section,they survival rate were 67 percent.in contrast of normal control group.30 minutes hypoension of MAP 30mmhg had produced brain injury.3.Group level of MAP25mmhg controlled for 30 mintues and Group level of MAP30mmhg controlled for 60 mintues survival rate were 38 percent,Hippocampal expression of HSP70 and cox-2 the degree higher,The degree of brain damage with the step-down and step-down time and increase the degree of increase.