McDonald K S, Delp M D, Fitts R H
Biology Department/Biological and Biomedical Research Institute, Marquette University, Milwaukee, Wisconsin 53233.
J Appl Physiol (1985). 1992 Jun;72(6):2210-8. doi: 10.1152/jappl.1992.72.6.2210.
The purpose of this study was to characterize the distribution of blood flow in the rat during hindlimb unweighting (HU) and post-HU standing and exercise and examine whether the previously reported (Witzmann et al., J. Appl. Physiol. 54: 1242-1248, 1983) elevation in anaerobic metabolism observed with contractile activity in the atrophied soleus muscle was caused by a reduced hindlimb blood flow. After either 15 days of HU or cage control, blood flow was measured with radioactive microspheres during unweighting, normal standing, and running on a treadmill (15 m/min). In another group of control and experimental animals, blood flow was measured during preexercise (PE) treadmill standing and treadmill running (15 m/min). Soleus muscle blood flow was not different between groups during unweighting, PE standing, and running at 15 m/min. Chronic unweighting resulted in the tendency for greater blood flow to muscles composed of predominantly fast-twitch glycolytic fibers. With exercise, blood flow to visceral organs was reduced compared with PE values in the control rats, whereas flow to visceral organs in 15-day HU animals was unaltered by exercise. These higher flows to the viscera and to muscles composed of predominantly fast-twitch glycolytic fibers suggest an apparent reduction in the ability of the sympathetic nervous system to distribute cardiac output after chronic HU. In conclusion, because 15 days of HU did not affect blood flow to the soleus during exercise, the increased dependence of the atrophied soleus on anerobic energy production during contractile activity cannot be explained by a reduced muscle blood flow.
本研究的目的是描绘大鼠在后肢去负荷（HU）期间、HU后站立和运动时的血流分布特征，并检查先前报道的（Witzmann等人，《应用生理学杂志》54: 1242 - 1248, 1983）萎缩比目鱼肌收缩活动时观察到的无氧代谢升高是否由后肢血流减少所致。在进行15天的HU或笼养对照后，在去负荷、正常站立和跑步机跑步（15米/分钟）期间用放射性微球测量血流。在另一组对照和实验动物中，在运动前（PE）跑步机站立和跑步机跑步（15米/分钟）期间测量血流。在去负荷、PE站立和15米/分钟跑步期间，两组之间比目鱼肌血流无差异。慢性去负荷导致流向主要由快肌糖酵解纤维组成的肌肉的血流有增加的趋势。运动时，与对照大鼠的PE值相比，内脏器官的血流减少，而15天HU动物的内脏器官血流不受运动影响。这些流向内脏和主要由快肌糖酵解纤维组成的肌肉的较高血流表明，慢性HU后交感神经系统分配心输出量的能力明显下降。总之，由于15天的HU在运动期间不影响比目鱼肌的血流，萎缩比目鱼肌在收缩活动期间对无氧能量产生的依赖性增加不能用肌肉血流减少来解释。
