Skeletal muscle derived NO and vascular regulation

描述（由申请人提供）： 在运动肌肉时，α-肾上腺素能血管收缩对局部抑制敏感， 骨骼肌收缩的代谢产物。称为功能性交感神经溶解，如 代谢调节抵消了交感神经激活对神经系统的有害影响， 肌肉灌注在上一个资助周期中，我们提供了啮齿类动物的多条证据， 一氧化氮（NO）是功能性交感神经溶解的关键介质。值得注意的是， 参与交感神经溶解的NO的主要来源似乎是NOS的神经元亚型 （nNOS），其在骨骼肌中高度富集。我们现在假设， 血管α-肾上腺素能受体上的骨骼肌来源的NO由两个 主要细胞内机制：（1）nNOS通过肌营养不良蛋白定位于肌膜 一种将nNOS的Ca 2+依赖性激活与肌肉强度偶联的复合物 收缩和促进NO扩散通过肌膜;和（2）在何种程度上，NO 被活性氧物质灭活，如骨骼肌中产生的超氧化物（O2）。 由于血管紧张素II（Ang II）是一种有效的刺激O2-超氧化物生成，我们 假设O2-超氧化物生成增加是损害 以肾素-血管紧张素激活为特征的病理生理状态下的交感神经溶解 系统我们进一步假设，在这种状态下， 运动肌肉中的血管收缩产生功能性肌肉缺血，触发 过度反射增加交感神经活动和血压。测试这些 假设，我们将使用互补的体内啮齿动物和人类模型。操纵 数量和细胞定位的nNOS在骨骼肌，我们将使用遗传小鼠模型 和腺病毒基因转移。为了增加血管紧张素II产生的O2-超氧化物，我们将使用 几种模型，包括大鼠和大鼠中的长时间Ang II输注和硝酸盐耐受， 人类该方案的特点是：（1）动物与动物的融合， 人类研究;（2）使用腺病毒基因治疗啮齿动物骨骼肌，以测试 关于局部血管调节的机制假说;（3）新的假说， 血管调节NO与骨骼肌nNOS的亚细胞定位;（4）新的 一种假说暗示骨骼肌来源的O2-超氧化物在产生 常见病理生理状态下的功能性肌肉缺血，其特征在于 肾素-血管紧张素系统，和（5）令人兴奋的潜在临床意义，这一点 假设驱动的研究。

DESCRIPTION (provided by applicant): In exercising muscles, alpha-adrenergic vasoconstriction is sensitive to inhibition by local metabolic products of skeletal muscle contraction. Termed functional sympatholysis, such metabolic modulation negates an otherwise deleterious effect of sympathetic activation on muscle perfusion. In the last grant cycle, we provided multiple lines of evidence in rodents and humans that nitric oxide (NO) is a key mediator of functional sympatholysis. Remarkably, the primary source of the NO involved in sympatholysis appears to be the neuronal isoform of NOS (nNOS) that is highly enriched in skeletal muscle. We now hypothesize that the bioavailability of skeletal muscle-derived NO at the vascular alpha-adrenergic receptors is determined by two major intracellular mechanisms: (1) localization of nNOS to the sarcolemma by the dystrophin complex which couples Ca2+-dependent activation of nNOS to the intensity of muscle contraction and facilitates NO diffusion across the sarcolemma; and (2) the extent to which NO is inactivated by reactive oxygen species, such as superoxide (O2) produced in skeletal muscle. Because angiotensin II (Ang II) is a potent stimulus for O2-superoxide production, we hypothesize that increased generation of O2-superoxide is a common mechanism impairing sympatholysis in pathophysiologic states characterized by activation of the renin-angiotensin system. We further hypothesize that in such states the resultant unopposed alpha-adrenergic vasoconstriction in exercising muscle produces functional muscle ischemia, triggering exaggerated reflex increases in sympathetic nerve activity and blood pressure. To test these hypotheses, we will use complementary in vivo rodent and human models. To manipulate the quantity and cellular localization of nNOS in skeletal muscle, we will use genetic mouse models and adenoviral gene transfer. To increase O2-superoxide production by Ang II, we will use several models including prolonged Ang II infusion and nitrate tolerance in both rats and humans. The distinctive features of this proposal include: (1) the integration of animal and human studies; (2) the use of adenoviral gene therapy of rodent skeletal muscle to test mechanistic hypotheses about local vascular regulation; (3) the novel hypothesis linking vascular regulation by NO with subcellular localization of nNOS in skeletal muscle; (4) the novel hypothesis implicating a pivotal role for skeletal muscle-derived O2-superoxide in producing functional muscle ischemia in common pathophysiologic states characterized by activation of the renin-angiotensin system, and (5) the exciting potential clinical implications of this hypothesis-driven research.