Coupled autoregulation models in the cerebro-vasculature

A non-dimensional representation of both myogenic and metabolic autoregulation coupled with an asymmetric binary tree algorithm simulating the cerebro-vasculature has been developed. Results are presented for an autoregulation algorithm of the cerebro-vasculature downstream of the efferent arteries, in this case the middle cerebral artery. These results indicate that, due to the low pressures found in the arteriolar structure, the myogenic mechanism based on the increased open probability due to pressure of stretched activated ion channels does not provide enough variation in the vascular resistance to support constancy of blood flow to the cerebral tissue under variable perfusion pressure. A metabolic model has been developed under the assumption of close proximity between venules and the vascular tree at the arteriolar level. This allows carbon dioxide to diffuse between arterioles and the venous bed causing either a relaxation or contraction of the nearby arteriolar bed. Results show that the metabolic mechanism seems to be the dominant mechanism for cerebral autoregulation.