Endothelial L-arginine pathway and regional cerebral arterial reactivity to vasopressin

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Abstract

Experiments were designed to characterize the mechanism of vasopressin action in small arteries of brain stem and cerebrum and to determine the role of L-arginine pathway in reactivity of these vessels to vasopressin. Secondary branches of canine basilar arteries (425 ± 63 μm ID, n = 6) and middle cerebral arteries (466 ± 30 μm ID, n = 6) were dissected and mounted on glass microcannulas in organ chambers. Changes in intraluminal diameter of the pressurized arteries were measured using a video dimension analyzer. Vasopressin caused endothelium-dependent relaxation in the brain stem arteries [-log half-maximal effective concentration (EC50) = 9.2 ± 0.4, n = 5] but not in the branches of middle cerebral-arteries. In contrast, bradykinin caused identical endothelium-dependent relaxations in arteries of both regions (-log EC50 = 8.0 ± 0.2, n = 5, and 7.7 ± 0.1, n = 4 for brain stem and cerebrum, respectively). Relaxations to vasopressin (but not to bradykinin) were reduced in the presence of V1-vasopressinergic antagonist [1-(β-mercapto-β-cyclopentamethylenepropionic acid),2-(O- methyl)tyrosine]arginine vasopressin [d(CH2)5-Tyr(Me)AVP;10-7 M], pertussin toxin (100 ng/ml), and N(G)-monomethyl-L-arginine (L-NMMA; 10-4 M). The inhibitory effect of L-NMMA was prevented by L-arginine (3 x 10-4 M) but not D-arginine (3 x 10-4 M). These studies suggest that vasopressin causes endothelium-dependent relaxation in canine brain stem arteries. The effect of the neuropeptide appears to be mediated by activation of endothelial V1-vasopressinergic receptors coupled to nitric oxide synthase. This signal transduction pathway is not functional in endothelial cells of branches of middle cerebral arteries.

Original languageEnglish (US)
Pages (from-to)H1557-H1562
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume262
Issue number5 31-5
DOIs
StatePublished - 1992

Keywords

  • G protein
  • V-vasopressinergic receptors
  • bradykinin
  • endothelium-derived relaxing factor
  • nitric oxide

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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