These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Inhibitory effect of melatonin on alpha1-adrenergic-induced vasoconstriction in mesenteric beds of spontaneously hypertensive rats.
    Author: Girouard H, de Champlain J.
    Journal: Am J Hypertens; 2004 Apr; 17(4):339-46. PubMed ID: 15062888.
    Abstract:
    BACKGROUND: The aim of this study was to assess the effects of melatonin on alpha1-adrenergic pathway in mesenteric arteries of spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. METHODS AND RESULTS: The SHR are characterized by a higher vasoconstriction (P < .001) and inositol phosphate formation (P < .001) in response to phenylephrine (PHE) and an increased superoxide anion production (P < .001) in mesenteric arteries. Melatonin and 2-iodomelatonin produced a significant inhibition of the PHE-induced vasoconstriction in isolated and perfused mesenteric beds (P < .001) with the same magnitude in SHR and WKY rats. Melatonin significantly decreased the inositol phosphate (IPs) formation in isolated mesenteric arteries from SHR compared to WKY rats (P < .001). The inhibitory effect of melatonin was increased by the removal of endothelium (P < .001). No effects of superoxide dismutase (SOD), tempol, or catalase were observed on the PHE-induced vasoconstriction. Moreover, no superoxide anion scavenging effect of 2-iodomelatonin was observed in isolated mesenteric vascular muscle cells using lucigenin. CONCLUSIONS: The present study showed that high melatonin concentrations inhibit the alpha1-adrenergic-induced vasoconstriction and inositol phosphate formation in mesenteric arteries from SHR and WKY rats. The vasorelaxant effect of the melatonin receptors agonist, 2-iodomelatonin, and the absence of any vasoactive effect of antioxidants such as SOD, tempol, and catalase suggest that melatonin exerts its inhibition on alpha1-adrenergic-induced vasoconstriction of mesenteric arteries through a low-affinity membrane receptor negatively coupled to the IPs formation and that this effect is independent of its antioxidant properties.
    [Abstract] [Full Text] [Related] [New Search]