Shear Stress Dependent Regulation of Vascular Resistance in Health and Disease: Role of Endothelium

For a long time, locally released metabolic factors from parenchymal cells and the myo-genic response of vascular smooth muscle were considered to be the two main peripheral regulatory mechanisms to control vascular resistance and thereby determining the distribution of blood flow and pressure within vascular networks of various organs of the body. However, not every change in blood flow could be satisfactorily explained by these two mechanisms. The “flow-dependent” responses of blood vessels, namely, an increase in blood flow in arteries followed by their dilation had already been observed at the beginning of this century, and perhaps even earlier, yet the nature and importance of this phenomenon in blood flow regulation was not delineated until recently. In the last two decades, especially following the recognition of the role of endothelium in the production of vasoactive factors, much new experimental evidence was gathered that suggests the general presence and importance of flow (shear stress)-depend...