School of Health Sciences, College of Health and Medicine, University of Tasmania, Hobart, Australia; Graduate Medicine, School of Medicine, University of Wollongong, Wollongong, Australia.
Graduate Medicine, School of Medicine, University of Wollongong, Wollongong, Australia.
Prostaglandins Leukot Essent Fatty Acids. 2019 Dec;151:37-44. doi: 10.1016/j.plefa.2019.08.006. Epub 2019 Aug 29.
Dietary fish oil provides polyunsaturated fatty acid (PUFA) docosahexaenoic acid (DHA) and is associated with modified oxygen consumption, contractile fatigue and physiological responses to ischaemia or hypoxia in striated muscle. This study systematically investigated the membrane incorporation of fatty acids, with a focus on DHA, into skeletal muscle in relation to functional/metabolic differences and their responsiveness to fish oil doses.
Male Sprague-Dawley rats were randomised to isoenergetic diets (10% fat by weight). Human Western-style diets were simulated with 5.5% tallow, 2.5% n-6 PUFA sunflower seed oil and 2% olive oil (Control). High-DHA tuna oil exchanged for olive oil provided a Low (0.32%) or moderate (Mod) (1.25%) fish oil diet. Membrane phospholipid fatty acid composition was analysed in samples of five skeletal muscles selected for maximum variation in muscle fibre-type.
Concentrations of DHA varied according to muscle fibre type, very strongly associated with fast oxidative glycolytic fibre population (r = 0.93; P < 0.01). No relationship was evident between DHA and fast glycolytic or slow oxidative fibre populations. Fish oil diets increased membrane incorporation of DHA in all muscles, mainly at the expense of n-6 PUFA linoleic and arachidonic acid.
The exquisite responsiveness of all skeletal muscles to as little fish oil as the equivalent of 1-2 fish meals per week in a human diet and the selective relationship to fatigable muscle fibre-types supports an integral role for DHA in muscle physiology, and particularly in fatigue resistance of fast-twitch muscles.
Skeletal muscle fibres vary according to structural, metabolic and neurological characteristics and ultimately influences contractile function. This study sort to determine if the composition of phospholipid polyunsaturated fatty acids (PUFA), incorporated in their membranes, might also differ according to fibre type and when omega-3 PUFA are made available in the diet. We systematically demonstrated that the omega-3 PUFA, docosahexaenoic acid (DHA), incorporated into skeletal muscle membranes well above its provision in the diet and without competitive influence of high omega-6 PUFA concentrations, typical to the Western-style human diet. Notably, incorporation preferentially occurred according to metabolic characteristics of each muscle, supporting the notion that DHA plays an integral role in fast oxidative glycolytic muscle fibres.
饮食中的鱼油提供多不饱和脂肪酸（PUFA）二十二碳六烯酸（DHA），并与横纹肌耗氧量、收缩疲劳和对缺血或缺氧的生理反应改变有关。本研究系统地研究了脂肪酸，特别是 DHA，在骨骼肌中的膜内掺入与功能/代谢差异及其对鱼油剂量的反应有关。
雄性 Sprague-Dawley 大鼠随机分配到等能量饮食（按重量计 10%脂肪）。用人的西式饮食模拟 5.5%牛脂、2.5% n-6PUFA 葵花籽油和 2%橄榄油（对照）。用高 DHA 金枪鱼油代替橄榄油提供低（0.32%）或中（Mod）（1.25%）鱼油饮食。对选择的五种骨骼肌样本进行膜磷脂脂肪酸组成分析，以最大程度地改变肌纤维类型。
DHA 的浓度因肌纤维类型而异，与快氧化糖酵解纤维群密切相关（r=0.93；P<0.01）。DHA 与快糖酵解或慢氧化纤维群之间没有明显的关系。鱼油饮食增加了所有肌肉的膜内 DHA 掺入，主要是通过牺牲 n-6PUFA 亚油酸和花生四烯酸。
人类饮食中每周相当于 1-2 餐鱼的情况下，所有骨骼肌对如此少量的鱼油的反应非常敏感，以及与易疲劳的肌纤维类型的选择性关系，支持 DHA 在肌肉生理学中具有重要作用，特别是在快肌的抗疲劳能力方面。
骨骼肌纤维根据结构、代谢和神经特点而变化，最终影响收缩功能。本研究旨在确定磷脂多不饱和脂肪酸（PUFA）的组成是否也因纤维类型而不同，以及当ω-3PUFA 在饮食中可用时。我们系统地证明了 ω-3PUFA，二十二碳六烯酸（DHA），在饮食中提供的水平以上掺入骨骼肌膜内，而不受典型的西式饮食中高ω-6PUFA 浓度的竞争影响。值得注意的是，掺入优先根据每个肌肉的代谢特征发生，这支持了 DHA 在快氧化糖酵解肌纤维中发挥重要作用的观点。
