Control of flow on the microvascular level

Abstract

The finding of a permanent perfusion of all brain capillaries under normal conditions raises the question of “How is cerebral blood flow distributed to the different capillaries?” Experiments, in which an intravascular dye was injected and its distribution to the brain capillaries was measured, have shown a heterogeneous capillary perfusion under normal conditions and a more homogeneous capillary perfusion during conditions of increased cerebral blood flow such as hypercapnia and whisker barrel stimulation. With such a mechanism, it is possible that, an enhanced exchange of blood gases and metabolic fuels and waste products is obtained, without the need of recruitment of previously non-perfused capillaries.