The blood velocity pattern near the cranial wall at the renal ostia, where atherosclerotic lesions are prone to develop, are characterized by 1) slow time-averaged shear rate, 2) separation of the flow, and 3) a time-varying oscillation of the flow (Arterioscler Thromb 1992; 12: 626-632). To elucidate the relation between the velocity pattern and localization of development of atherosclerosis, we analyzed the fine structure and function of the vascular wall by using laser scanning confocal microscope. In a Wistar rat the renal artery was perfusion fixed at a pressure of 75 mmHg. F-actin and DNA in nuclei were stained with rhodamine phalloidin and bisBenzimide, respectively. Low density lipoprotein (LDL) scavenger transport was investigated by injection of DiI-Ac-LDL before sacrificed. At the cranial wall, where atherosclerotic lesions as prone to develop, the shapes of endothelial cells and nuclei were relatively round, comparing to the caudal wall or the distal portion of renal artery, where atherosclerotic lesions hardly develop. The orientation of nuclei and stress fibers at the cranial wall was relatively random. With ten minutes incubation, Ac-LDL were observed in the endothelial cell and smooth muscle cell with higher density in the former. The density of Ac-LDL in vascular media at the cranial wall was much higher than that the caudal wall. In conclusion, the velocity pattern localizes the development of atherosclerosis via the change in the endothelial cell structure and Ac-LDL transport within the vascular wall.
