Skeletal muscle performance and cellular adaptations to high hemoglobin-oxygen affinity

项目概要/摘要 这项工作的总体目标是研究骨骼肌的新的翻译思想 在人类运动过程中氧气（O2）运输级联的背景下的性能。该提案 由一个特殊的导师团队的支持，并将提供非常有前途的申请人显著 支持他成为翻译整合生理学独立研究者的目标。具体 目的是利用申请人在骨骼肌生理学方面的专业知识和 关于人体血流调节的优秀导师团队（赞助商，Joyner博士），骨骼肌和 线粒体生物学（共同发起人，Lanza博士），骨骼肌成像技术（合作者，Port博士）和 血红蛋白（Hb）变体（合作者，Hoyer和Oliveira博士）。具体目标1将测试是否高Hb- O2亲和力将加剧骨骼肌疲劳，并减少骨骼肌O2提取过程中 使人疲劳的运动我们将在持续60秒的最大持续时间内评估膝关节伸肌的疲劳程度。 自愿等长收缩，我们将评估血液和呼出气体浓度使用序贯 分别从径向导管和波形二氧化碳描记术采集血样。我们假设疲劳会 与对照组相比，具有高Hb-O2亲和力的人肌肉中的O2释放更大，O2释放更少。 具体目标2将测试高Hb-O2亲和力是否会加剧运动诱导的代谢 在骨骼肌中的蓄积和灌注增加。我们将评估骨骼肌生物能量学 通过厌氧代谢产生的代谢副产物（H+、Pi和H2 PO 4-）的积累， （同时）使用交错磷向运动的膝伸肌灌注血液 磁共振波谱（31 P-MRS）和动脉自旋标记（ASL）。我们假设 高Hb-O2患者运动相关代谢物的积累和充血反应更大 与对照相比的亲和力。具体目标3将测试骨骼的生理适应是否 肌纤维类型组成和线粒体氧化能力发生在高Hb-O2人群中 亲和力我们将评估骨骼肌纤维肌球蛋白重链的表达和线粒体的氧化能力。 使用组织化学染色技术（SDS-PAGE和银染色）和高分辨率 呼吸测定法（Oxygraph-2k和Datlab软件）。我们假设骨骼肌纤维 肌球蛋白重链的表达将向更高比例的糖酵解纤维和线粒体转移， 与对照组相比，具有高Hb-O2亲和力的人的氧化呼吸能力将降低。这 该提案将测试与O2运输级联和运动骨骼肌相关的基本概念， 人类申请人和导师团队，结合马约诊所的广泛资源， 提供最佳的培训环境，以完成拟议的目标。

Project Summary/Abstract The overall goal of the proposed work is to investigate novel translational ideas about skeletal muscle performance in the context of the oxygen (O2) transport cascade during exercise in humans. The proposal is supported by an exceptional mentorship team and will provide the highly promising applicant significant support in his goal of becoming an independent investigator in translational integrative physiology. The specific aims leverage the applicant’s expertise in skeletal muscle physiology and the distinct expertise of the meritorious mentorship team on regulation of blood flow in humans (sponsor, Dr. Joyner), skeletal muscle and mitochondrial biology (co-sponsor, Dr. Lanza), skeletal muscle imaging techniques (collaborator, Dr. Port) and hemoglobin (Hb) variants (collaborators, Drs. Hoyer and Oliveira). Specific Aim 1 will test whether high Hb- O2 affinity will exacerbate skeletal muscle fatigue and reduce skeletal muscle O2 extraction during fatiguing exercise. We will assess fatigue of the knee extensor muscles during a sustained, 60-s maximal voluntary isometric contraction and we will assess blood and expired gas concentrations using sequential blood samples from radial catheters and waveform capnography, respectively. We hypothesize that fatigue will be greater and O2 offloading at the muscle will be less in people with high Hb-O2 affinity compared to controls. Specific Aim 2 will test whether high Hb-O2 affinity will exacerbate exercise-induced metabolic accumulation and increase in perfusion to skeletal muscle. We will assess skeletal muscle bioenergetics via the accumulation of metabolic by-products produced from anaerobic metabolism (H+, Pi and H2PO4-) and (simultaneously) perfusion of blood to the exercising knee extensor muscles using interleaved phosphorous magnetic resonance spectroscopy (31P-MRS) and arterial spin labeling (ASL). We hypothesize that there will be a greater accumulation of exercise-related metabolites and hyperemic response in patients with high Hb-O2 affinity compared to controls. Specific Aim 3 will test whether physiological adaptations of skeletal muscle fiber type composition and mitochondrial oxidative capacity occur in people with high Hb-O2 affinity. We will assess skeletal muscle fiber myosin heavy chain expression and mitochondrial oxidative capacity using histochemical staining techniques (SDS-PAGE and silver staining) and high-resolution respirometry (Oxygraph-2k and Datlab software), respectively. We hypothesize that skeletal muscle fiber myosin heavy chain expression will be shifted toward higher proportions of glycolytic fibers and mitochondrial oxidative respiratory capacity will be reduced in people with high Hb-O2 affinity compared to controls. This proposal will test fundamental concepts related to the O2 transport cascade and exercising skeletal muscle in humans. The applicant and mentorship team, combined with the extensive resources at the Mayo Clinic, provide the optimal training environment to complete the proposed aims.