Lanfranconi Francesca, Borrelli Emma, Ferri Alessandra, Porcelli Simone, Maccherini Massimo, Chiavarelli Mario, Grassi Bruno
Department of Science and Biomedical Technologies, University of Milan, Milan, Italy.
Med Sci Sports Exerc. 2006 Aug;38(8):1374-83. doi: 10.1249/01.mss.0000228943.62776.69.
The main aim of the present study was to investigate skeletal muscle oxidative metabolism in heart transplant recipients (HTR) by noninvasive tools.
Twenty male HTR (age 50.4 +/- 2.6 yr; mean +/- SE) and 17 healthy untrained age-matched controls (CTRL) performed an incremental exercise (IE) and a series of constant-load (CLE) moderate-intensity exercise tests on a cycloergometer. The following variables were determined: heart rate (HR); breath-by-breath pulmonary O2 uptake (VO2); and skeletal muscle (vastus lateralis) oxygenation indices by continuous-wave near-infrared spectroscopy. Changes in concentration of deoxygenated hemoglobin (Hb) and myoglobin (Mb) (Delta[deoxy(Hb + Mb)]), expressed as a fraction of values obtained during a transient limb ischemia, were taken as an index of skeletal muscle O2 extraction. "Peak" values were determined at exhaustion during IE. Kinetics of adjustment of variables were determined during CLE.
VO2peak, HRpeak, and Delta[deoxy(Hb + Mb)] peak were significantly lower in HTR than in CTRL (17.1 +/- 0.7 vs 34.0 +/- 1.9 mL.kg(-1).min(-1), 133.8 +/- 3.8 vs 173.0 +/- 4.8 bpm, and 0.42 +/- 0.03 vs 0.58 +/- 0.04, respectively). In HTR, Delta[deoxy(Hb + Mb)] increase at submaximal workloads was steeper than in CTRL, suggesting an impaired O2 delivery to skeletal muscles, whereas the lower Delta[deoxy(Hb + Mb)] peak values suggest an impaired capacity of O2 extraction at peak exercise. VO2 and HR kinetics during CLE were significantly slower in HTR than in CTRL, whereas, unexpectedly, no significant differences were found for Delta[deoxy(Hb+Mb)] kinetics (mean response time: 21.3 +/- 1.1 vs 20.2 +/- 1.2 s).
The findings confirm the presence of both "central" (cardiovascular) and "peripheral" (at the skeletal muscle level) impairments to oxidative metabolism in HTR. The noninvasiveness of the measurements will allow for serial evaluation of the patients, in the presence and/or absence of rehabilitation programs.
本研究的主要目的是通过无创工具调查心脏移植受者（HTR）的骨骼肌氧化代谢情况。
20名男性HTR（年龄50.4±2.6岁；均值±标准误）和17名年龄匹配的健康未经训练的对照者（CTRL）在功率自行车上进行递增运动（IE）和一系列恒定负荷（CLE）中等强度运动测试。测定以下变量：心率（HR）；逐次呼吸肺氧摄取量（VO₂）；以及通过连续波近红外光谱法测定的骨骼肌（股外侧肌）氧合指数。以肢体短暂缺血期间获得的值的分数表示的脱氧血红蛋白（Hb）和肌红蛋白（Mb）浓度变化（Δ[脱氧（Hb + Mb）]）被用作骨骼肌氧提取指数。“峰值”在递增运动期间力竭时测定。在恒定负荷运动期间测定变量的调整动力学。
HTR的VO₂峰值、HR峰值和Δ[脱氧（Hb + Mb）]峰值显著低于CTRL（分别为17.1±0.7 vs 34.0±1.9 mL·kg⁻¹·min⁻¹、133.8±3.8 vs 173.0±4.8次/分钟，以及0.42±0.03 vs 0.58±0.04）。在HTR中，次最大负荷下Δ[脱氧（Hb + Mb）]的增加比CTRL更陡峭，表明向骨骼肌的氧输送受损，而较低的Δ[脱氧（Hb + Mb）]峰值表明峰值运动时氧提取能力受损。HTR在恒定负荷运动期间的VO₂和HR动力学明显比CTRL慢，而意外的是，Δ[脱氧（Hb + Mb）]动力学未发现显著差异（平均反应时间：21.3±1.1 vs 20.2±1.2秒）。
研究结果证实HTR在氧化代谢方面存在“中枢”（心血管）和“外周”（骨骼肌水平）损害。测量的无创性将允许在有和/或没有康复计划的情况下对患者进行系列评估。
