不同鼠龄大鼠颈总动脉内膜弹力纤维退行性变性的实验研究

Experimental study of the internal elastic laminae in the bifurcation of the common carotid artery in rats of different age

目的探讨颈总动脉分叉处内弹力膜超微结构的增龄变化，为临床防治老年性脑血管病提供实验依据。方法24只Wistar大鼠，按月龄分为青年组、成年组和老年组，每组8只。快速分离各年龄组Wistar大鼠的颈总动脉分叉，热碱消化提纯内弹力膜，运用扫描电镜结合图像分析仪测量内弹力膜的窗孔数目和窗孔面积。结果成年组内弹力膜窗孔数（964±4）大于青年组（710±1）和老年组（624±2）（P〈0．01）；老年和青年组间差异无统计学意义。老年组大窗孔数（105±9）大于青年组（13±1）和成年组（52±3）（P〈0．01）；成年组大于青年组（P〈0．01）。老年组窗孔面积百分比（39．86±3．51）％大于青年组（15．52±1．70）％和成年组（23．58±2．12）％（P〈0．01），成年与青年组间差异无统计学意义。结论随增龄颈总动脉分叉处弹性减少、窗孔变大，内膜对大分子物质的屏障性降低，可能是动脉粥样硬化和动脉瘤好发于颈总动脉分叉处的重要原因。

Objective To explore the differences of ultrastructure in internal elastic laminae （IEL） of common carotid artery among young, adult and aged rats in order to provide evidences for prevention and therapy of cerebrovascular disease in aged people. Methods Twenty-four male Wistar rats, aged from 3 months to 3 years, were divided into young, adult and aged group. The IEL in the bifurcation of the right common carotid artery was isolated and digested with hot alkali. The luminal surface of each IEL was observed by the scanning electric microscope. The number and the area of fenestration in the IEL were measured and compared among three different age groups. Results The number of fenestration was the hightest in the adult （964±4）, which was significantly higher than that in the young （710± 1） or in the aged group （624± 2）（P〈0.01 ）, but the difference was not significant between aged and young rats （P〉0.05）. The number of large fenestration was significantly elevated with age increasing and the differences among 3 groups were significant [adult （52 ± 3） , young （13 ± 1） , aged （105 ± 9） , P〈0.01 ]. The mean percentage of fenestration area was also remarkably increased with age [adult （23.58±2.12）%, young （15.52± 1.70）%, aged （39.86±3.51）%, P〈0.01 ], which was not significantly different between the adult and the young rats. Conclusion The age-related decrease in elasticity and ablitity of preventing penetration of macromolecules in the IEL may be a crucial reason for higher incidences of atherosclerosis and aneunynoma in the bifurcation of common carotid artery in aged rats.