Endothelial-mediated regulation of cerebral microcirculation.

Vascular endothelial cells are important not only for maintaining homeostasis, but also in pathogenesis of vascular disorders. Cerebral capillary and microvascular endothelial cells play an active role in maintaining cerebral blood flow, microvascular tone and blood brain barrier functions. Factors produced and released by endothelial cells, other brain cells and circulating blood cells participate in these regulatory functions. In particular, endothelin-1 (ET-1) and nitric oxide (NO) are known to contribute to the functional vascular changes under pathological conditions (e.g., hypertension, arteriosclerosis, and stroke). This report describes the involvement of endothelial cell mediators in the post-ischemic hypoperfusion induced by brain ischemia and in vitro endothelial responses (Ca(2+) mobilization and cytoskeletal rearrangements) to ET-1 and its interactions with NO or 2-AG. The capacity of NO and endocannabinoids to counteract ET-1-induced cerebral capillary and microvascular endothelial responses indicates that they may actively participate in EC function and implicates them in physiological and pathophysiological conditions.