Flow modulation and recruitment in a theoretical model for blood flow regulation in heterogeneous microvascular networks

Abstract

A theoretical model is presented for metabolic blood flow regulation in realistic heterogeneous network structures, derived from previously published experimental results from hamster cremaster muscle in control and dilated states. The model is based on modulation of arteriolar diameters, according to the length‐tension characteristics of vascular smooth muscle. Responses of smooth muscle cell tone to myogenic, shear‐dependent, and metabolic stimuli are included. Blood flow is simulated, including unequal hematocrit partition at diverging vessel bifurcations. Convective and diffusive oxygen transport in the network is simulated, and oxygen‐dependent metabolic signals are assumed to be conducted upstream from distal vessels to arterioles. Simulations were carried out over a range of tissue oxygen demand. With increasing demand, arterioles dilated, blood flow increased, and the numbers of flowing arterioles and capillaries – defined by red cell flux above a small threshold value – increased. Unequal hematocrit partition at bifurcations contributed to this behavior. These results imply that vessel recruitment, as observed in the hamster cremaster preparations, can occur as a consequence of local control of arteriolar tone. Supported by NIH grant HL070657.