The Neurovascular Unit: Focus on the Regulation of Arterial Smooth Muscle Cells.

The neurovascular unit is a physiological unit present in the brain, which is constituted by elements of the nervous system (neurons and astrocytes) and the vascular system (endothelial and mural cells). This unit is responsible for the homeostasis and regulation of cerebral blood flow. There are two major types of mural cells in the brain, pericytes and smooth muscle cells. At the arterial level, smooth muscle cells are the main components that wrap around the outside of cerebral blood vessels and the major contributors to basal tone maintenance, blood pressure and blood flow distribution. They present several mechanisms by which they regulate both vasodilation and vasoconstriction of cerebral blood vessels and their regulation becomes even more important in situations of injury or pathology. In this review, we discuss the main regulatory mechanisms of brain smooth muscle cells and their contributions to the correct brain homeostasis.