Blood flow and O₂ extraction as a function of O₂ uptake in muscles composed of different fiber types

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• 作者：Leonardo F. Ferreira ; Paul McDonough ; Brad J. Behnke ; Timothy I. Musch and David C. Poole
• 关键词：Microvascular none ; color ; black" href="/science?_ob=MathURL&_method=retrieve&_udi=B6X16-4HVW8C2-1&_mathId=mml78&_user=10&_cdi=7234&_rdoc=5&_handle=V-WA-A-W-E-MsSAYVW-UUA-U-AAZCWEEZAY-AAZWYYUVAY-VBWYDVYV-E-U&_acct=
• 刊名：Respiratory Physiology & Neurobiology
• 出版年：2006
• 期刊代码：185_15699048
• 类别：bio
• 出版时间：27 October 2006
• 卷：153
• 期：3
• 页码：237-249
• 文件大小：556 K

摘要

We examined how the greater vasodilatory capacity of slow- (ST) versus fast-twitch (FT) muscles impacts the relationship between blood flow () and O₂ uptake () and, consequently, the O₂ extraction (a-v_O2 diff.)-to- relationship. was measured with radiolabelled microspheres, while was calculated by the Fick principle using measurements of microvascular O₂ pressure (phosphorescence quenching) at rest, low- (2.5 V) and high-intensity contractions (4.5 V) for soleus (Sol; ST, n = 5), mixed-gastrocnemius (MG; FT, n = 7) and white-gastrocnemius (WG; FT, n = 7). The slope of the -to- relationship () was not different among muscles (Sol = 5.5 ± 0.2, MG = 6.0 ± 0.11 and WG = 5.8 ± 0.06; P > 0.05). In contrast, the intercept was greater (P < 0.05) for Sol (16.3 ± 2.7 ml min⁻¹ 100 g⁻¹) versus MG and WG (in ml min⁻¹ 100 g⁻¹: 1.39 ± 0.26 and 1.45 ± 0.23, respectively; MG and WG, P > 0.05). In addition, the a-v_O2 diff.-to- relationship for Sol was shifted rightward compared to MG and WG. These data suggest that the increase in for a given change in is similar for slow- and fast-twitch muscles, at least for the range of metabolic rates and muscles studied herein and that a-v_O2 diff. differences result from the lower resting in FT muscles.