Thubrikar M J, Keller A C, Holloway P W, Nolan S P
Department of Surgery, University of Virginia Health Sciences Center, Charlottesville 22908.
Atherosclerosis. 1992 Nov;97(1):1-9. doi: 10.1016/0021-9150(92)90045-i.
Atherosclerosis occurs focally in branch segments of the artery. Understanding why these segments are more susceptible to the development of the disease is at the root of understanding atherogenesis. We investigated accumulation of low density lipoprotein (LDL) in the branch and non-branch regions of the aorta to determine why the disease develops in branch regions. Abdominal aortas and their major branches were harvested from 36 rabbits. Rabbit LDL was prepared from whole blood and radiolabeled with 125I. The aorta was incubated with radiolabeled LDL in the lumen at 37 degrees C, under intraluminal pressure of 2-3 mmHg, for 1 h. Disks of 1.8 mm diameter were punched from the branch and non-branch regions of the aorta, cryosectioned and the sections counted in a gamma counter. Protein bound radioactivity was determined by TCA precipitation. LDL accumulation was highest towards the aortic intima and declined sharply towards the media. LDL accumulation at any given depth was higher in the branch than non-branch region. LDL accumulation in the intimal-medial sections was 87% higher in the branch than non-branch region. Total LDL accumulation in the branch was almost twice that in the non-branch region. Mean LDL accumulation was also greater in the branch than non-branch region. The aorta was significantly thicker at the branch. LDL distribution profiles indicate that LDL is present in a greater concentration and over a greater depth in the branch than non-branch region. The tendency of the branch region to accumulate LDL in greater amounts may explain its susceptibility to atherosclerotic lesion development.
动脉粥样硬化在动脉的分支段局部发生。理解为何这些节段更易患该疾病是理解动脉粥样硬化发生机制的根本所在。我们研究了低密度脂蛋白（LDL）在主动脉分支和非分支区域的蓄积情况，以确定该疾病为何在分支区域发展。从36只兔子身上采集腹主动脉及其主要分支。从全血中制备兔LDL并用125I进行放射性标记。将主动脉在腔内压力为2 - 3 mmHg、37摄氏度的条件下，与放射性标记的LDL在腔内孵育1小时。从主动脉的分支和非分支区域冲压出直径为1.8 mm的圆片，进行冷冻切片，然后在γ计数器中对切片进行计数。通过三氯乙酸沉淀法测定蛋白质结合的放射性。LDL的蓄积在主动脉内膜处最高，并向中膜急剧下降。在任何给定深度，分支区域的LDL蓄积都高于非分支区域。内膜 - 中膜切片中，分支区域的LDL蓄积比非分支区域高87%。分支区域的总LDL蓄积几乎是非分支区域的两倍。分支区域的平均LDL蓄积也高于非分支区域。分支处的主动脉明显更厚。LDL分布曲线表明，与非分支区域相比，分支区域LDL的浓度更高，且分布深度更大。分支区域更易大量蓄积LDL的倾向可能解释了其易患动脉粥样硬化病变的原因。
