人工寒潮对高血压和正常血压大鼠脑血管收缩反应性的不同影响

Different cerebrovascular responsiveness following artificial cold exposure in renovascular hypertensive rats and normal SD rats

目的:检测肾血管高血压大鼠(RHR)和SD大鼠离体大脑中动脉(MCA)对于血管收缩剂的张力反应差异,探讨ACE对不同血压大鼠脑血管反应性的不同影响及其意义.方法:将双肾双夹(2k2c)法复制成功的RHR[SBP>200mm-Hg(1mmHg=0.133kPa)]及正常血压的SD大鼠各分为寒潮和非寒潮共4组(6只/组),单笼放置于ACE和室温环境3d后,显微操作分离MCA制作离体动脉环,等张收缩法测定离体血管张力及其对于受体依赖药(phe,U46619,ET-1)和非受体依赖的(高K+)血管收缩剂的反应.结果:①人工寒潮减弱SD大鼠phe,U46619,ET-1和高K+诱导MCA的血管收缩反应;②与SD相比,以上血管收缩反应在RHR都隆低;③对于RHR而言,人工寒潮对于RHR的MCA血管收缩反应与室温组相比没有统计学改变.结论:严重高血压的RHR脑动脉功能受损,其MCA血管收缩反应能力低于SD,而且在寒冷时丧失了进一步减弱收缩的调节保护能力.

AIM： To examine the influence of artificial cold exposure （ACE） on cerebrovascular responses to receptor-dependent and receptor-independent vasoconstrictors in renovascular hypertensive rat（RHR） and normal SD rat. METHODS： Twenty- four rats were randomly divided into 4 groups： RHR, RHT ＋ ACE, SD and SD ＋ ACE （ n = 6/group）. RHR（ SBP 〉 200 mm-Hg） was reproduced by two-kidney and two-clip （2k2c） way. Segments of the middle cerebral artery （MCA） from the 4 groups were mounted in Multi Myograph System for measurement of isometric contractions and cumulative concentration-dependent contraction to endothelin-1, U46619, phenylephrine, and extracellular K^＋ in normal Kreb＇s solution. RESULTS： There was no significant difference in vasoconstriction induced by phenylephfine, thrombexane A2 analog U-46619, endothelin-1 or high K^＋ in MCA between RHR and RHR ＋ ACE. However, the constrictions to these constrictors were reduced in RHR and RHR ＋ ACE compared with vessels from SD and SD ＋ ACE. CONCLUSION： ACE results in a significant reduction in vasoconstfictive response to both receptor-dependent and -independent constrictors in MCA of SD rats, not RHR.