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  • Title: Impaired function of alpha2-adrenergic autoreceptors on sympathetic nerves associated with mesenteric arteries and veins in DOCA-salt hypertension.
    Author: Luo M, Fink GD, Lookingland KJ, Morris JA, Galligan JJ.
    Journal: Am J Physiol Heart Circ Physiol; 2004 Apr; 286(4):H1558-64. PubMed ID: 14670814.
    Abstract:
    The present study tested the hypothesis that there is impaired function of alpha(2)-adrenergic autoreceptors and increased transmitter release from sympathetic nerves associated with mesenteric arteries and veins from DOCA-salt rats. High-performance liquid chromatography was used to measure the overflow of ATP and norepinephrine (NE) from electrically stimulated mesenteric artery and vein preparations in vitro. In sham arteries, nerve stimulation evoked a 1.5-fold increase in NE release, whereas in DOCA-salt arteries there was a 3.9-fold increase in NE release over basal levels (P < 0.05). In contrast, stimulated ATP release was not different in DOCA-salt arteries compared with sham arteries. In sham veins, nerve stimulation evoked a 2.9-fold increase in NE release, whereas in DOCA-salt veins there was a 8.4-fold increase in NE release over basal levels (P < 0.05). In sham rats NE release, normalized to basal levels, was greater in veins than in arteries (P < 0.05). The alpha(2)-adrenergic receptor antagonist yohimbine (1 microM) increased ATP and NE release in sham but not DOCA-salt arteries. The alpha(2)-adrenergic receptor agonist UK-14304 (10 microM) decreased ATP release in sham but not DOCA-salt arteries. In sham veins, UK-14304 decreased, but yohimbine increased, NE release; effects that were not observed in DOCA-salt veins. These data show that nerve stimulation causes a greater increase in NE release from nerves associated with veins compared with arteries. In addition, impairment of alpha(2)-adrenergic autoreceptor function in sympathetic nerves associated with arteries and veins from DOCA-salt rats results in increased NE release.
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