Essential Hypertension and Human Skin Blood Flow

描述（由申请方提供）：人体皮肤循环是一种可接近的代表性血管床，用于体内检查导致原发性高血压（HT）血管功能障碍的机制。这项建议是我们以前的工作调查的血管机制的基础上的年龄和高血压相关的变化，在控制反射介导的皮肤血流量增加的逻辑延伸。拟议的研究扩展了我们以前的研究，通过配对国家的最先进的一氧化氮（NO）的具体在体内的方法（局部加热和皮内微透析）在体外分析的人皮肤样本，以检查受损的皮肤血管舒张（VD）信号传导的人类HT的精确信号机制。与HT相关的血管功能障碍是多方面的，但涉及NO生物利用度的整体降低，这是由组成性NO-氧化酶（内皮和神经元NOS）表达和活性受损以及氧化应激增加引起的。虽然，皮肤NO依赖性血管性痴呆是明确衰减高血压的人在NO合成的NOS异构体产生NO的变化是未解决的。增强的诱导型NOS和衰减的组成型NOS同工酶与HT相关的炎症和肾上腺素能神经血管状态有关。推测的HT诱导的减少血管系统中组成型NOS的NO合成的机制包括（1）炎症诱导的iNOS合成的NO增加，其改变了NOS酶动力学（Km降低）通过S-亚硝基化，（2）血液动力学诱导的NOS上调--如果NOS底物L-精氨酸（L-arg）（3）由于L-arg和/或必需辅因子（四氢生物蝶呤（BH 4））的可用性不足，通过未偶联的NOS产生的氧化剂增加。通过L-鸟氨酸介导的多胺和脯氨酸的合成增加，上调的精氨酸酶也与高血压诱导的血管壁重塑的发病机制有关。因此，有一种机制将炎症、上调的NOS、NOS解偶联和有害的血管壁重塑与HT联系起来。拟议的调查将在体内和体外的方法来检查炎症，氧化应激和NO的生产之间的联系，在人类皮肤血管HT。具体目标1将检查NOS亚型介导减弱的皮肤NO依赖性，具体目标2将检查NOS酶在通过组成型NOS调节L-精氨酸可用性以用于NO合成中的作用，具体目标3将检查氧化应激和辅因子BH 4可用性的作用，因为它们与NOS解偶联有关。我们还将通过测量真实的时间相对氧化剂产生来研究上调的NOS和BH 4缺乏对NOS解偶联的机制联系。公共相关性：美国四分之一的人口未确诊或正在接受原发性高血压治疗。这种健康问题是普遍存在的，并要求情感，身体和经济成本。这些研究结果将为高血压对皮肤血管的影响提供新的重要信息。此外，这些结果将提供深入了解皮肤血流的调节和高血压血管病理的潜在治疗干预策略。

DESCRIPTION (provided by applicant): The human cutaneous circulation is an accessible, representative vascular bed for in vivo examination of mechanisms that contribute to vascular dysfunction with essential hypertension (HT). This proposal is a logical extension of our previous work investigating the vascular mechanisms underlying age and hypertensive-related changes in the control of reflex-mediated increases in skin blood flow. The proposed studies expand our previous research by pairing state-of-the-art nitric oxide (NO) specific in vivo methodologies (local heating and intradermal microdialysis) with in vitro analysis of human skin samples to examine the precise signaling mechanisms underlying impaired cutaneous vasodilatory (VD) signaling in humans with HT. Vascular dysfunction associated with HT is multifaceted but involves global decreases in NO bioavailability induced by impairments in constitutive NO-synthases (endothelial and neuronal NOS) expression and activity as well as increased oxidant stress. Although, cutaneous NO-dependent VD is clearly attenuated in hypertensive humans alterations in NO synthesis from the NOS isoforms producing NO are unresolved. Augmented inducible NOS and attenuated constitutive NOS isozymes are implicated in the inflammatory and hyperadrenergic neurovascular state associated with HT. Putative HT-induced mechanisms decreasing NO synthesis from the constitutive NOSs in the vasculature include (1) an inflammatory-induced increase in iNOS- synthesized NO which changes arginase enzyme kinetics (decreased Km) through S-nitrosylation, (2) a hemodynamic-induced upregulation of arginase-- both of which serve to limit NO synthesis through constitutive NOSs due to preferential metabolism if the NOS substrate L-arginine (L-arg) by arginase-- and (3) an increase in oxidant production through uncoupled NOS due to inadequate L-arg and/or essential cofactor (tetrahydriobiopterin (BH4)) availability. Upregulated arginase is also linked to the pathogenesis of hypertension-induced vessel wall remodeling through increased L-ornithine-mediated polyamine and proline synthesis. Thus, there is a mechanism linking inflammation, upregulated arginase, NOS uncoupling and deleterious vessel wall remodeling with HT. The proposed investigation will pair in vivo and in vitro methodologies to examine the putative link between inflammation, oxidant stress, and NO production in the cutaneous vasculature of humans with HT. Specific Aim 1 will examine the NOS isoforms mediating attenuated cutaneous NO-dependent, Specific Aim 2 will examine the role of arginase in regulating L-arginine availability for NO synthesis through the constitutive NOSs, and Specific Aim 3 will examine roles of oxidative stress and cofactor BH4 availability as they relate to NOS uncoupling. We will also examine the mechanistic link between upregulated arginase and BH4 deficiency on NOS uncoupling by measuring real time relative oxidant production. PUBLIC RELEVANCE: One quarter of the population in the United States has undiagnosed or is being treated for essential hypertension. This health issue is pervasive and exacts emotional, physical, and financial costs. The results from these proposed studies will provide new and important information on the vascular effects of hypertension in the skin. Further, these results will provide insight into the regulation of skin blood flow and potential therapeutic intervention strategies for hypertensive vascular pathology.