Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Service de Pneumologie, 2725, chemin Sainte-Foy, Québec G1V 4G5, Canada.
Thorax. 2010 Feb;65(2):113-7. doi: 10.1136/thx.2009.117168. Epub 2009 Aug 30.
A majority of patients with idiopathic pulmonary arterial hypertension (IPAH) display persistent exercise intolerance despite new specific therapies. Whether patients with IPAH exhibit peripheral muscle dysfunction that may contribute to this limitation remains unknown. The hypothesis that the muscles of patients with IPAH are weaker and display morphological changes compared with those of control subjects and that those changes partly correlate with their exercise capacity was tested.
To characterise quadriceps function, morphology and the enzymatic profile of patients with IPAH.
Exercise capacity, limb muscle cross-sectional area by CT scan, quadriceps strength by maximal voluntary contraction and non-volitional magnetic stimulation of the femoral nerve (quadriceps twitch; TWq), and muscle morphology and enzymatic profile by quadriceps biopsy of 10 patients with IPAH were compared with those of 10 matched controls subjects.
Patients with IPAH displayed a lower proportion of type I muscle fibres (p=0.05), a lower maximal voluntary contraction (p=0.05) and TWq (p=0.01), and an increased muscular phosphofructokinase/3-hydroxyacyl-CoA-dehydrogenase ratio (p=0.05). They also tended to have lower thigh muscle cross-sectional area (p=0.15). Maximal oxygen uptake correlated with quadriceps strength (R(2)=0.42, p=0.04), and oxygen uptake at anaerobic threshold correlated with muscle oxidative capacity assessed by oxidative enzyme level for citrate synthase (R(2)=0.45, p=0.05) and 3-hydroxyacyl-CoA-dehydrogenase (R(2)=0.86, p<0.01), and type I fibre capillarity (R(2)=0.57, p=0.02).
Patients with IPAH present significant peripheral muscle changes that partly correlated with their exercise capacity.
尽管有新的特定治疗方法，大多数特发性肺动脉高压（IPAH）患者仍表现出持续的运动不耐受。IPA 患者是否存在可能导致这种限制的外周肌肉功能障碍仍不清楚。本研究旨在检验 IPAH 患者的肌肉较弱且存在形态学变化，且这些变化部分与运动能力相关的假设。
描述 IPAH 患者的股四头肌功能、形态和酶谱特征。
对 10 例 IPAH 患者和 10 例匹配对照者的运动能力、CT 扫描四肢肌肉横截面积、股神经最大随意收缩和非随意磁刺激（股四头肌 twitch；TWq）的股四头肌力量、股四头肌活检的肌肉形态和酶谱进行了比较。
与对照组相比，IPA 患者的 I 型肌纤维比例较低（p=0.05），最大自主收缩力（p=0.05）和 TWq 较低（p=0.01），磷酸果糖激酶/3-羟酰基辅酶 A 脱氢酶比值较高（p=0.05）。IPA 患者的大腿肌肉横截面积也较低（p=0.15）。最大摄氧量与股四头肌力量相关（R²=0.42，p=0.04），无氧阈时的摄氧量与柠檬酸合酶（R²=0.45，p=0.05）和 3-羟酰基辅酶 A 脱氢酶（R²=0.86，p<0.01）的氧化酶水平以及 I 型肌纤维毛细血管密度（R²=0.57，p=0.02）相关。
IPA 患者存在显著的外周肌肉变化，这些变化部分与运动能力相关。
