A theoretical model for flow regulation in the cerebral cortex: role of penetrating arterioles

Abstract

Activation of a region of the brain results in a local increase in blood flow, a process known as neurovascular coupling (NVC). Here, a theoretical model of blood flow regulation in the cerebral cortex is utilized to investigate the potential role of penetrating arterioles as the primary mechanism for local control of blood flow. Penetrating arterioles connect pial arterioles with the capillary meshwork deeper in the cortex and have a typical length of approximately 600 μm. This is about one‐sixth of the length of corresponding small arterioles in skeletal muscle. The question arises whether these relatively short arterioles can achieve the range of flow modulation observed in the cerebral cortex. A previously developed compartmental model for flow regulation in skeletal muscle was modified to represent the structure of cerebral microvasculature. A compartment consisting of penetrating arterioles with a reference diameter of 14.8 μm and a length of 600 μm is assumed to provide active control of blood flow. Smooth muscle tone in these arterioles is assumed to depend on a combination of signals representing myogenic, shear‐dependent, and metabolic responses. The metabolic response is represented by a change in endothelial cell membrane potential, propagated upstream along arterioles by conducted responses. Sensitivity of diameter to membrane potential was determined based on experimental data. According to the model, a hyperpolarization of 40 mV can result in an increase in local blood flow by approximately 70%. Since increases in local blood flow of 50% with activation have been observed, these results imply that vasoconstriction and vasodilation by penetrating arterioles can provide typical levels of blood flow control seen in neurovascular coupling.