alpha-Stimulation protects exercise increment in skeletal muscle oxygen consumption.
alpha-Stimulation protects exercise increment in skeletal muscle oxygen consumption.
复制标题
α-刺激可保护骨骼肌耗氧量的运动增量。
作者：
S. Nellis;S. Flaim;K. M. McCauley;R. Zelis
在离体、自灌流、静态运动的犬股薄肌（2.5%P0）上，研究了持续输注去甲肾上腺素（NE）和机械阻断（MO）引起的低血流量（Q）状态下的耗氧量（VO 2）。在静息时（Qc和VO 2c）、运动5分钟后（Qe和VO 2 e）以及使用NE或MO运动5分钟后（Qt和VO 2 t）评估Q和VO 2。将数据标准化并绘制为VO_（2 e-VO_（2 t））/（VO_（2c-VO_（2 e））vs.（Qe-Qt）/（Qc-Qe），并确定NE的直线方程（y = 0.090x + 0.048）和MO的直线方程（y = 0.488x + 0.070）。经协方差分析检验，直线斜率差异显著（P <0.005）。这些数据表明，当NE减少Q在运动过程中，运动引起的VO 2保护到更大的程度比MO减少Q在类似的条件下。为了确定NE对VO 2的影响是否继发于β-肾上腺素能受体介导的骨骼肌代谢过程，在普萘洛尔β-阻滞剂存在下重复实验。在β受体阻滞剂的存在下，NE对骨骼肌VO 2的影响没有改变。因此，假设NE的这种作用的机制可能是由于血流重新分布到更活跃的肌纤维区域而导致氧提取效率的增加。
Oxygen consumption (VO2) in an isolated, autoperfused, statically exercising canine gracilis muscle (2.5% P0) was studied in low blood flow (Q) states induced by constant norepinephrine (NE) infusion and by mechanical occlusion (MO). Q and VO2 were evaluated at rest (Qc and VO2c), after 5 min of exercise (Qe and VO2e) and after 5 more min of exercise with either NE or MO (Qt and VO2t). Data were normalized and plotted as the VO2e-VO2t)/(VO2c-VO2e) vs. (Qe-Qt)/(Qc-Qe) and equations of the lines for NE (y = 0.090x + 0.048) and for MO (y = 0.488x + 0.070) were determined. The slopes of the lines, tested by analysis of covariance, were significantly different (P less than 0.005). These data indicate that when NE reduced Q during exercise, the exercise induced in VO2 was protected to a greater degree than when MO reduced Q under similar conditions. To determine if the effect of NE on VO2 was secondary to a beta-adrenergic-receptor-mediated of skeletal muscle metabolic processes, the experiments were repeated in the presence of beta-blockade with propranolol. In the presence of beta-blockade, the effects of NE on skeletal muscle VO2 were unchanged. It is therefore hypothesized that the mechanism of this effect of NE may be an increase in the efficiency of oxygen extraction resulting from a redistribution of blood flow to more active muscle fiber regions.