Human Aging, Exercise & FMD: Translational Physiology

描述（由申请人提供）：这是R01 AG13038的竞争性更新提案，目前已连续第八年获得资助。该奖项的重点是研究衰老和生活方式干预对大动脉功能和结构的影响。在目前的计划中，我们建议通过测试以下紧密关注的工作假设来继续我们在这一主题上的富有成效的工作：1)定期的中等强度有氧运动（每天快走）增加外周导管动脉血流介导的扩张（FMD），这是一种内皮依赖性血管扩张能力和整体动脉血管健康的测量，以前久坐不动的中老年人；2)提高一氧化氮（NO）生物利用度是规律有氧运动改善口蹄疫的关键机制；3)增加一氧化氮合成的关键辅助因子四氢生物蝶呤（BH4）的生物利用度是定期有氧运动增加一氧化氮生物利用度和FMD的机制之一；4)血管氧化应激的降低，部分与细胞外超氧化物歧化酶（ecSOD）的增加有关，是定期有氧运动增加BH4和NO生物利用度和FMD的重要机制；5)动脉内皮细胞中特定基因编码蛋白表达的变化（即酶促抗氧化、eNOS和磷酸化eNOS蛋白表达的增加，氧化酶、内皮素-1和血管紧张素II受体蛋白表达的降低）是规律有氧运动对氧化应激、BH4和NO生物利用度以及FMD有利作用的关键分子机制之一。为了验证这些假设，我们将在久坐的健康中老年（55-75岁）男性和女性中进行两项互补的随机有氧运动干预试验。血管氧化应激、BH4和NO生物利用度的变化在FMD改善中的机制作用将在12周运动（或非运动注意控制）条件之前和之后进行的实验中确定。研究人员将利用一种新的翻译生理学研究技术来深入了解相关的分子机制，通过定量免疫荧光来确定参与调节这些细胞和系统适应习惯性运动的基因的动脉内皮细胞蛋白表达的变化。预期的结果将为中等有氧运动对恢复中老年人久坐不动的动脉内皮功能的功效及其潜在机制提供新的、重要的临床见解。特别是，拟议的研究将提供关于两种高度新颖的机制的第一个信息，通过这些机制，定期运动可以增加NO的生物利用度：1)通过增加BH4的生物利用度；2)通过改变参与决定内皮功能的关键动脉内皮细胞蛋白的表达。

DESCRIPTION(provided by applicant): This is a competitive renewal proposal for R01 AG13038, currently in its 8th consecutive year of funding. The focus of this award has been to study the effects of aging and lifestyle interventions on large artery function and structure. In the present plan we propose to continue our productive work on this theme by testing the following tightly focused set of working hypotheses: 1) regular moderate-intensity aerobic exercise (daily brisk walking) increases peripheral conduit artery flow-mediated dilation (FMD), a measure of endothelium-dependent vasodilatory capacity and overall arterial vascular health, in previously sedentary middle-aged and older adults; 2) an increase in nitric oxide (NO) bioavailability is the key mechanism by which regular aerobic exercise improves FMD; 3) an increase in the bioavailability of the critical co-factor for NO synthesis, tetrahydrobiopterin (BH4), is one mechanism by which regular aerobic exercise increases NO bioavailability and FMD; 4) a reduction in vascular oxidative stress, related in part to an increase in extracellular superoxide dismutase (ecSOD), is an important mechanism by which regular aerobic exercise increases BH4 and NO bioavailability and FMD; 5) changes in the expression of proteins encoded by specific genes in arterial endothelial cells (i.e., increases in enzymatic antioxidant, eNOS, and phosphorylated eNOS protein expressions, and reductions in oxidant enzyme, endothelin-1, and angiotensin II receptor protein expressions) are among the key molecular mechanisms associated with the favorable effects of regular aerobic exercise on oxidative stress, BH4 and NO bioavailability, and FMD. To test these hypotheses we will conduct 2 complementary randomized aerobic exercise intervention trials in sedentary healthy middle-aged and older (age 55-75 years) men and women. The mechanistic roles played by changes in vascular oxidative stress and BH4 and NO bioavailability in mediating improvements in FMD will be determined in experimental sessions conducted before and after a 12-week exercise (or non-exercise attention control) condition. Insight into the molecular mechanisms involved will be obtained using a novel translational physiology research technique by which changes in arterial endothelial cell protein expression of genes involved in the regulation of these cellular and systemic adaptations to habitual exercise will be determined via quantitative immunofluorescence. The expected results will provide new, clinically important insight into the efficacy of moderate aerobic exercise for restoring arterial endothelial function in middle-aged and older sedentary adults, and the underlying mechanisms. In particular, the proposed research will provide the first information on 2 highly novel mechanisms by which regular exercise may augment NO bioavailability: 1) by increasing BH4 bioavailability; and 2) by producing changes in the expression of key arterial endothelial cell proteins involved in determining endothelial function.