Loss of Arterial Dilation in the Reendothelialized Area of the Flow-Loaded Rat Common Carotid Artery

Abstract We have investigated regenerated endothelial cells and their possible contribution to arterial dilation in response to increased blood flow in rat common carotid artery (CCA). After endothelial denudation using a balloon catheter in the left CCA, an arteriovenous shunt was constructed between the left CCA and the left external jugular vein at 20 mm distal from the orifice in the denuded group. Animals that were given the arteriovenous shunt without denudation were used to form the nondenuded group. The blood flow rate in the left CCA was increased by sixfold after operation in the denuded group. We observed that endothelial cells were gradually regenerated from the orifice to the distal area and that the reendothelialized area after 4 to 8 weeks was approximately one third of the left CCA (5.31±1.49 mm at 4 weeks, 5.47±1.56 mm at 8 weeks). In the reendothelialized area of the left CCA after 4 to 8 weeks, the lumen diameter was significantly smaller than that of the nondenuded group and showed no significant difference from age-matched nonsurgical animals. The intimal and medial thickening, which would result in arterial stenosis in the reendothelialized area, was not observed in the denuded group, although the denuded control showed significant intimal thickening. From these results, we conclude that regenerated endothelial cells reduce intimal thickening but do not respond to increased blood flow to dilate the artery.