Abstract
In connection with a symposium of the main subject “Role of Hemorheological Factors in Atherogenesis” some problems are discussed concerning the permeability of artery walls to clarify the role of hemorheological factors.
Recent experimental results of the permeability of artery walls by Fry and Nerem et al. are summarized. The pathways of macromolecules through endothelial cells are classified into two categories: passage along junctions between endothelial cells, and transport by vesicles through pinocytosis.
From the peculiar rheological properties of protoplasm, such as non-Newtonian viscosity, viscoelasticity and thixotropy, a molecular picture of protoplasm in endothelial cells is drawn. Based on such a molecular picture, a theoretical interpretation of the increase in the permeability of artery walls with increase in hemorheological factors is given.
Theoretical considerations are given about the mechanism of endothelial injury caused by hemorheological factors. Scanning electron micrographs of injured endothelium show complete falling away of endothelial cells. However, it seems difficult to consider sudden falling away of endothelial cells due to shear stress or turbulence.
Since the junctions are rather weak portions within the endothelium, those portions of endothelial cells which are quite close to the junctions are liable to be “peeled off” a bit at the initial stage of hemorheological effects. Such a local peeling of cells will then develop into a complete falling away of endothelial cells in a long period of time.
