Pre-conditioning exercise attenuates capillary regression in atrophied soleus muscle

Abstract

Purpose: We have investigated structural alterations of the capillary network in the rat soleus muscle after 2-wk hindlimb unloading with and without pre-conditioning exercise. Methods: To clarify three-dimensional architecture of capillary network, contrast medium-injected sections were visualized clearly with a confocal laser scanning microscope. Fifteen male Wistar rats were used in this study. They were randomly divided into a control group, a hindlimb unloading without pre-conditioning exercise and with pre-conditioning exercise. Pre-conditioning exercise was performed treadmill running (20 m/min, 20°grade, 25min) before hindlimb unloading. Results: After hindlimb unloading, the cross-sectional area of muscle fiber and muscle mass were significantly decreased in with and without exercise. The mean capillary density, the number of anastomotic capillaries, the tortuosity of capillaries and capillary luminal diameter were significantly smaller in hindlimb unloading than in age-matched control. However, in hindlimb unloading with pre-conditioning exercise, these were significantly higher compared with hindlimb unloading without exercise. Concluding Remarks: Although hindlimb unloading conditions resulted in a significant decrease the capillary network, results from the present investigation indicate that the pre-conditioning exercise attenuated the regression of muscle capillary in hindlimb unloading rats. [Jpn J Physiol 55 Suppl:S121 (2005)]