Remodeling in Three-Dimensional Capillary Architecture and Vascular apoptosis in the Atrophic Slow Twitch Muscle

Abstract

Purpose: We have investigated structural alterations of the capillary network and vascular apoptosis in the soleus muscle of rats after 2wks of hindlimb unloading. Methods: Ten male Wistar rats (aged 10 wks old) were used. They were randomly divided into a control group (n=5, CONT) and a hindlimb unloading group (n=5, HS). Three-D architecture of microvasculature of the soleus and the apoptosis of vascular endothelial cell were morphometrically examined using confocal laser scanning microscope. Results: The cross-sectional area of muscle fiber and muscle mass were significantly decreased in HS. The number of longitudinal capillaries paralleling muscle fiber did not change with atrophy in the soleus muscle. However, the mean capillary density, the number of anastomotic capillaries and capillary luminal diameter were significantly smaller in HS than in age-matched CONT. In addition, the tortuosity of capillaries was significantly decreased and TUNEL positive nuclei were observed in atrophied muscle. Concluding Remarks: These results indicate that muscle atrophy by unloading the hindlimb generates structural alterations of capillary network, and apoptosis appears to occur in vascular endothelial cell of longitudinal and/or tortuous capillaries. [Jpn J Physiol 54 Suppl:S122 (2004)]