Heterogeneous pO2 distribution as a consequence of the capillary network.

Abstract

The interconnectedness of the capillary network gives rise to a heterogeneous capillary fow distribution. Model studies have demonstrated that at normal overall perfusion some capillaries may receive no or little flow. However, capillary flow is an important factor in determining the degree of metabolic supply to adjacent tissue cells. Since the work of Krogh (1918), oxygen transport in capillary systems and tissue has been studied intensively. In the present model known non-linearities, such as the oxygen binding by the erythrocytes, the consumption rate in tissue cells and the resistance to diffusion of the capillary wall and cell membranes, are linearized. On the other hand the often oversimplified capillary network and capillary flow distribution have been added to the model allowing the study of convective mixing of confluent capillary blood flow. This is important for the description of tissue supply distal from a bifurcation. Moreover, the intercapillary distance in several organs is small, permitting diffusional shunting. The present three dimensional capillary and tissue network model has been based on observations of casts of the myocardial microcirculation (Bassingthwaighte et al., 1974; Tomanek et al., 1982).