HUMAN AGING, EXERCISE AND ENDOTHELIUM-DEPENDENT VASODILATION: TRANSLATIONAL PHY

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。在本计划中，我们提出了以下假设：1）定期中等强度的有氧运动（每日快走）增加先前久坐的中老年人的外周导管动脉血流介导的舒张（FMD），这是内皮依赖性血管舒张能力和总体动脉血管健康的量度; 2）一氧化氮（NO）生物利用度的增加是规律有氧运动改善FMD的关键机制; 3）NO合成的关键辅因子四氢生物蝶呤（BH 4）的生物利用度的增加是规律有氧运动增加NO生物利用度和FMD的一种机制; 4）部分与细胞外超氧化物歧化酶（ecSOD）增加相关的血管氧化应激的减少是规律有氧运动增加BH 4和NO生物利用度和FMD的重要机制; 5）动脉内皮细胞中由特定基因编码的蛋白质表达的变化（即，酶促抗氧化剂eNOS和磷酸化eNOS蛋白表达的增加，以及氧化酶、内皮素-1和血管紧张素II受体蛋白表达的减少）是与规律有氧运动对氧化应激、BH 4和NO生物利用度以及FMD的有利作用相关的关键分子机制。为了验证这些假设，我们将在久坐的健康中年和老年（年龄55-75岁）男性和女性中进行2项补充随机有氧运动干预试验。在12周运动（或非运动注意力控制）条件之前和之后进行的实验中，将确定血管氧化应激和BH 4和NO生物利用度的变化在介导FMD改善中所起的机制作用。深入了解所涉及的分子机制将获得使用一种新的翻译生理学研究技术，通过这种技术，动脉内皮细胞蛋白质表达的变化，参与这些细胞和系统适应习惯性运动的调节基因将通过定量免疫荧光测定。预期的结果将为中度有氧运动恢复中老年久坐成年人动脉内皮功能的功效及其潜在机制提供新的、具有临床重要意义的见解。特别是，拟议的研究将提供有关2种高度新颖的机制的第一个信息，通过这种机制，定期运动可以增加NO的生物利用度：1）通过增加BH 4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。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In the present plan we propose to test the following 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.