Flow-induced control of arterial lumen.

Blood flow velocity is a factor that affects the diameter of arteries. In order to investigate the flow-induced arterial dilatation, the outer diameter of the femoral, common carotid or renal arteries of anaesthetized cats was measured during perfusion of these arteries with blood or plasma-substituting solutions under conditions of stabilized perfusion pressure. It has been shown that, whatever the perfusate, blood or a substituent, an increase in flow makes the artery to dilate. Consequently, the flow-induced dilatation is not due to any blood-borne humoral factor. As an increase in the solution's viscosity causes dilatation even at constant flow-rate and pressure in the artery, the effect is to be ascribed to the ability of the vascular wall to perceive shear stress. As far as removal of endothelium eliminates the dilatation evoked by increasing flow or fluid viscosity, it may be concluded that the flow-induced dilatation is due to the sensitivity to shear stress of the endothelium.