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  • Title: Modulation of extraluminally induced vasoconstrictions by endothelium-derived nitric oxide in the canine basilar artery.
    Author: Minato H, Hashizume M, Masuda Y, Hosoki K.
    Journal: Arzneimittelforschung; 1995 Jun; 45(6):675-8. PubMed ID: 7544129.
    Abstract:
    The present study was undertaken to investigate the role of endothelium in extraluminally induced vasospasm of the cerebral artery using isolated perfused canine basilar arteries. The extraluminal applications of high K+ and prostaglandin F2 alpha (PGF2 alpha) induced concentration-dependent vasoconstriction. Both constrictive responses were significantly enhanced by denuding endothelium. Additionally, the responses in the endothelium-intact arteries were markedly augmented by intraluminal perfusion with NG-monomethyl-L-arginine (L-NMMA). These results suggest that the inhibition of nitric oxide (NO) synthase in endothelium enhances increase in transmembrane Ca(2+)-influx which is a common constrictive mechanism to the vasoconstrictors. The augmentative action induced by L-NMMA was inhibited by intraluminal perfusion of L-arginine, but not by D-arginine. Furthermore, the augmentation was not observed in the arteries without endothelium. These results suggest that the endothelium may have a great significance on responsiveness to extraluminal vasoactive substances and that endothelium-derived NO may modulate the extraluminally induced vasoconstriction which is responsible for cerebral vasospasm after subarachnoid hemorrhage.
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