Effect of blood viscocity on arterial flow induced dilator response.

Experiments were designed to determine whether blood viscosity affects flow induced dilator response in conduit arteries. Changes in diameter of the femoral artery of anaesthetised cats evoked by stepwise blood flow increases were recorded at normal blood viscocity, at haemodilution, and at haemoconcentration, under conditions of stabilised transmural pressure. Dilator responses caused by the same increments in flow rate increased at haemoconcentration and decreased at haemodilution, in parallel with the changes in blood viscocity. These data show that haemodilution attenuates and haemoconcentration augments flow induced dilatation, and they confirm the suggestion that flow induced arterial dilatation is due to endothelial sensitivity to shear stress.