A model for upstream signalling in the control of capillary blood flow

Abstract

Blood supply to tissues is controlled through vasoconstriction and vasodilation activated by components of the vascular wall and smooth muscle cells. Local oxygen saturation and wall shear stress play an important role in this process and wall shear stress has a role in capillary and venular flow as well as flow in arterioles and arteries. Local capillary networks can dilate to increase flow but there is little clear evidence of how local capillary networks act to increase arteriolar blood flow when needed. Pulsatile flow plays an important part in signalling wall shear stress within the vascular system and it has recently been shown that pulse pressure changes can be efficiently transmitted along soft walled fluid filled tubes such as blood vessels. This confirms that pulse pressure within the system can maintain downstream flow; it also raises the question of whether pulse pressure changes can signal upstream from local capillary beds to the supplying arteriole.