原发性高血压大鼠血浆外泌体水平及其与微循环变化的相关性研究

摘要

目的:研究13周龄原发性高血压大鼠(SHR)外周血外泌体数量和大小分布与微循环功能的相关性.方法:市购13周龄雄性SHR(实验组)和相同周龄的WKY大鼠(对照组)各7只.采用多功能激光多普勒血流探测仪(LDF)检测两组大鼠耳廓、趾及脑皮质血流量、血细胞聚集度和血流速度,采用血流成像技术(LDPI)观察脑皮质血流分布.取外周血,提取血浆外泌体,采用透射电镜观察外泌体形态,以Apogee流式细胞术检测总外泌体水平和直径＜100nm的外泌体水平,分析实验组大鼠外泌体水平与其微循环指标的相关性.结果:LDF结果显示,实验组大鼠脑皮质血流量和血流速度均显著高于对照组(P＜0.05或P＜0.01),而实验组大鼠趾血流量和血流速度明显低于对照组(P＜0.05),两组大鼠的耳廓血流量、血流速度及耳廓、趾和脑皮质的血细胞聚集度差异均无统计学意义(P＞0.05);LDPI结果显示,实验组大鼠脑皮质血流灌注量显著高于对照组(P＜0.01).体外实验显示,实验大鼠血浆外泌体大小分布不均,但以直径＜100nm者居多;实验组总外泌体水平和直径＜100nm外泌体水平均明显高于对照组(P＜0.05).相关性分析显示,实验组大鼠血浆总外泌体和直径＜ 100nm外泌体水平与脑皮质血流量呈显著正相关(P＜0.01).结论:脑微循环功能改变与血浆总外泌体含量,尤其直径＜100nm的外泌体水平显著相关,提示外泌体水平的升高可能预警原发性高血压发生和发展过程中的微循环变化,或可作为高血压早期的监测标记物.%Objective:To investigate the microcirculation function and its correlation to the concentration and size distribution of circulating exosomes in spontaneous hypertensive rats(SHR).Method:Study group included seven 13-week-old male SHR,control group included seven 13-week-old male Wistar-Kyoto(WKY) rats.The blood flow,blood flow velocity,blood cell aggregation of all animals' cerebral cortices,auricles and toes were detected by the high power laser doppler flowmetry(LDF),and the whole distribution curve of blood flow of their cerebral cortices were measured by the laser doppler perfusion imaging(LDPI).The exosomes were extracted from the plasma,and then detected by transmission electron microscopy.Last,the total concentration of exosomes and the concentration of exosomes with diameter less than 100nm were measured using Apogee flow cytometry.Results:LDF showed that the blood flow and blood flow velocity of cerebral cortex were both significantly higher in study group than con trols(P＜0.05 or P＜0.01),while the blood flow and blood flow velocity of toes were both significantly lower in study group than in control group(P＜0.05 or P＜0.01),and the blood cell aggregation of cerebral cortices,auri cles and toes showed no differences between the two groups(P＞0.05).LDPI showed that the blood flow of cerebral cortex was significantly higher in study group than in control group(P＜0.01).Furthermore,the total concentration of exosomes from plasma was significantly higher in study group than control group(P＜0.05),and the same as the exosomes with diameter less than 100nm (P＜0.05).And most importantly,we found that the total concentration of exosomes and the concentration of exosomes with diameter less than 100nm from plasma were both positively related to the blood flow in cerebral cortex detected by LDPI(P＜0.01).Conclusion:The change of brain microcirculation function was significantly related to circulating total concentration of exosomes,especially to the concentration of exosomes with diameter less than 100nm.This indicated that the increase of exosomes might predict microcircula tion change in the processes and development of essential hypertension and could be a potential biomarker in the early stage of hypertension.