FUNCTION OF VASOACTIVE FACTORS IN THE CEREBRAL MICROCIRCULATION

The properties of brain capillary endothelial cells (BCECs) have been analyzed. BCECs express two types of receptor sites for endothelins (ETs), and ET(A)-like receptor, and an ET(B)-like receptor that is not coupled to phospholipase C but whose occupancy activates Na+/H+ exchange activity. The ET(A) receptor is positively coupled to phospholipase C and negatively coupled to adenylate cyclase. BCECs, unlike aortic endothelial cells, express high-affinity receptor sites for C-type natriuretic peptide. They respond to exogenous nitric oxide (NO) and to NO donor molecules by large activations of soluble guanylate cyclase, They produce little cGMP in response to A23187 or to agonists of phospholipase C but do so after an exposure to interleukin-1. The physiological consequence of the high reactivity of BCECs to vasoactive factors is discussed.