A Study on the Interrelations of the Hemodynamics and the Vascualr Endothelial Ultrastructure and Function

点击翻译按钮获取中文摘要

To interrelate low shear stress conditions in vivo, endothelial microfilament bundle formation and intimal plaque formation, we introduced a mild aortic stenosis in hypercholesterolemic fat-fed beagles. Shear stress was calculated from the instantaneous velocity profiles reconstructed from the data obtained with a 80 channel 20 MHz pulsed Doppler velocimeter. The amount of endothelial microfilament bundles was evaluated as the ratio of the integrated area filled with microfilaments to the total area of the endothelial cell (F/C) on transmission electron photomicrographs. Three sites were compared : 10 mm proximal to the stenosis (PROX), immediately upstream from the the stenosis (ST) and immediately distal to the stenosis (DISY). Shear stress was increased at ST and decreased at DIST as compared with PROX. A positive correlation was noted between shear stress and F/C (r=0.94, p<0.01). Intimal plaques were formed exclusively immediately distal to the stenosis, where shear stress was significantly low. We have also developed an in vitro shear stress loading instrument to study the alterations in various cell responses under variable shear stress conditions. Thus, low shear stress conditions may attenuate endothelial microfilament bundle formation and may promote the formation of intimal plaques under atherogenic conditions.