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遗传性高胆固醇血症患者骨骼肌小动脉中内皮依赖性舒张机制的改变。

Altered mechanisms of endothelium-dependent dilation in skeletal muscle arterioles with genetic hypercholesterolemia.

作者信息

Stapleton Phoebe A, Goodwill Adam G, James Milinda E, Frisbee Jefferson C

机构信息

Center for Interdisciplinary Research in Cardiovascular Science, Department of Physiology and Pharmacology, Robert C. Byrd Health Sciences Center, West Virginia University School of Medicine, Morgantown, WV 26505, USA.

出版信息

Am J Physiol Regul Integr Comp Physiol. 2007 Sep;293(3):R1110-9. doi: 10.1152/ajpregu.00410.2007. Epub 2007 Jul 11.

Abstract

With most cardiovascular disease risk factors, endothelium-dependent dilation of skeletal muscle resistance arterioles is compromised, although with hypercholesterolemia, impairments to reactivity are not consistently observed. Using apolipoprotein E (ApoE) and low-density lipoprotein receptor (LDLR) gene deletion male mouse models of hypercholesterolemia at 20 wk of age, we tested the hypothesis that arteriolar dilation would be maintained due to an increased stimulus-induced production of dilator metabolites via cyclooxygenase and cytochrome P-450 epoxygenase pathways. Arterioles from both strains demonstrated mild reductions in dilation to hypoxia and acetylcholine versus responses in C57/Bl/6J (C57) controls. However, although inhibition of nitric oxide synthase (NOS) attenuated dilation in arterioles from C57 controls, this effect was absent in ApoE or LDLR strains. In contrast, cyclooxygenase-dependent portions of dilator reactivity were maintained across the three strains. Notably, although combined NOS and cyclooxygenase inhibition abolished arteriolar responses to hypoxia and acetylcholine in C57 controls, significant reactivity remained in ApoE and LDLR strains. Whereas inhibition of cytochrome P-450 omega-hydroxylase and epoxygenases had no effect on this residual reactivity in ApoE and LDLR strains, inhibition of 12/15-lipoxygenase with nordihydroguaiaretic acid abolished the residual reactivity. With both hypoxic and methacholine challenges, arteries from ApoE and LDLR strains demonstrated an increased production of both 12(S)- and 15(S)-hydroxyeicosatetraenoic acid, end products of arachidonic acid metabolism via 12/15-lipoxygenase, a response that was not present in C57 controls. These results suggest that with development of hypercholesterolemia, mechanisms contributing to dilator reactivity in skeletal muscle arterioles are modified such that net reactivity to endothelium-dependent stimuli is largely intact.

摘要

对于大多数心血管疾病风险因素而言,骨骼肌阻力小动脉的内皮依赖性舒张功能受损,不过在高胆固醇血症中,反应性受损情况并不一致。我们使用20周龄的载脂蛋白E(ApoE)和低密度脂蛋白受体(LDLR)基因缺失的高胆固醇血症雄性小鼠模型,来检验以下假设:由于刺激诱导的扩张性代谢产物通过环氧化酶和细胞色素P-450环氧合酶途径产生增加,小动脉舒张功能将得以维持。与C57/Bl/6J(C57)对照相比,两种品系的小动脉对缺氧和乙酰胆碱的舒张反应均轻度降低。然而,尽管抑制一氧化氮合酶(NOS)可减弱C57对照小动脉的舒张功能,但在ApoE或LDLR品系中却不存在这种效应。相反,三种品系中扩张反应性的环氧化酶依赖性部分得以维持。值得注意的是,尽管联合抑制NOS和环氧化酶可消除C57对照小动脉对缺氧和乙酰胆碱的反应,但ApoE和LDLR品系中仍存在显著的反应性。虽然抑制细胞色素P-450ω-羟化酶和环氧合酶对ApoE和LDLR品系中的这种残余反应性没有影响,但用去甲二氢愈创木酸抑制12/15-脂氧合酶可消除残余反应性。在缺氧和乙酰甲胆碱刺激下,ApoE和LDLR品系的动脉均显示12(S)-和15(S)-羟基二十碳四烯酸的生成增加,这是花生四烯酸通过12/15-脂氧合酶代谢的终产物,而C57对照中不存在这种反应。这些结果表明,随着高胆固醇血症的发展,骨骼肌小动脉中有助于扩张反应性的机制发生了改变,从而使对内皮依赖性刺激的净反应性基本保持完整。

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