Cerebral Blood Flow in Acute Hypertension

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Abstract
Cerebral blood flow (CBF) was measured in rabbits subject to acute hypertension produced by angiotensin infusion. Hypertension led to cerebral hyperperfusion at the time of maximum systolic blood pressure (MSBP) with hypoperfusion five minutes post-MSBP. Focal cortical areas of greatly decreased flow were found at MSBP and up to 60 minutes post-MSBP. These regions were located primarily in arterial boundary zones, were confined to cortex, and were usually larger than the territory supplied by a single penetrating cortical arteriole. Angiotensin infused into carotid arteries had no direct effect on CBF. Passive vasodilation and intense vasoconstriction may coexist and breakdown of the blood-brain barrier may result from vascoconstriction rather than passive vasodilation. Locations of ischemic lesions in arterial boundary zones remain unexplained but may reflect an unusual degree of reactivity of vessels in those regions.