Myogenic (Stretch-Induced) and Flow-Regulated Tone of Human Pial Arteries
The normally functioning cerebral circulation effectively autoregulates, the vascular adjustments responsible for this probably occurring in pial arteries of all sizes. It has been shown that changes in diameter of cerebral blood vessels of several animal species can take place in response to perivascular neural (constrictor or dilator) activity, and through local mechanisms in the vessel wall responsive to intraluminal pressure and flow. A variety of factors, mainly metabolic, influence the intracerebral vasculature (for referencesseeref. 1). In this chapter, we will describe experimental observations on the pressure and flow-initiated changes in vascular tone of human pial arteries obtained during surgery. These vessels were transported to the Totman Laboratory from various Neurosurgical Centers for experimentation. Only the larger cerebral arteries are influenced by sympathetic nerves. Dilator nerves influence has yet to be observed in human arteries of any size (seeChapter 6).2Thus, it would seem likely that stretch-induced myogenic contraction and shear stress-initiated changes in tone are the dominant local regulating processes for human arteries.
KeywordsFlow Response Arterial Diameter Smooth Muscle Tone Pressure Step Myogenic Response
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