Affiliation:
1. Department of Physical Therapy, Faculty of Rehabilitation Niigata University of Health and Welfare Niigata Japan
2. Institute for Human Movement and Medical Sciences Niigata University of Health and Welfare Niigata Japan
3. Department of Rehabilitation Sciences, Graduate School of Medical Sciences Kitasato University Sagamihara Japan
4. Department of Rehabilitation Kitasato University School of Allied Health Sciences Sagamihara Japan
Abstract
ABSTRACTObjectiveTo clarify the effect of growth and advancing age on lymphatic capillarization in rat skeletal muscles, we examined the histological and biochemical changes of lymphatic capillaries in different fiber types of skeletal muscles across juvenile, young, and middle‐aged generations.MethodsWe collected the tibialis anterior (TA), extensor digitorum longus (EDL), and soleus (SOL) muscles. Immunohistochemical staining using LYVE‐1 and CD31 markers was used for lymphatic and blood capillaries, respectively. Real‐time PCR was used to analyze mRNA expression of lymphangiogenic factors.ResultsThe density of LYVE‐1‐positive lymphatic capillaries in the muscles peaked during the juvenile period and subsequently decreased with increasing age. In contrast to blood capillaries, fast‐twitch dominant muscles (i.e., TA and EDL) exhibited an age‐related decrease in lymphatic capillaries. Similar to blood capillaries, lymphatic capillaries were abundant in SOL, a slow‐twitch dominant muscle, which showed less susceptibility to age‐related lymphatic decline. The mRNA expression of lymphangiogenic factors was significantly upregulated in SOL and decreased in all muscles of middle‐aged rats.ConclusionsThe age‐related decrease of lymphatic capillaries in fast‐twitch muscles might be associated with age‐related muscle atrophy.