The brain is highly dependent on an adequate delivery of oxygen and glucose from the circulation, and cerebral blood flow (CBF) reductions impair neuronal function and, if protracted, induce brain damage. 12 Consequently, cerebrovascular control mechanisms assure that the delivery of oxygen and glucose is well matched to the energy demands of the cellular constituents of the brain. HTN induces profound alterations of these regulatory mechanisms, which, in concert with the structural changes described above, compromise the blood supply to the brain. Next, we examine the major mechanisms regulating the cerebral circulation and their perturbation by HTN.