Tsutsumi E.1, Murata Y.2
1Nisikyusyu University, Rehabilitation, Kanzaki, Japan, 2Saga University, Medicine, Saga, Japan
Background: Degenerative change of muscle fibers occurs accompanying the disease.
In diabetes mellitus various abnormalities were reported about muscle fibers, e.g. fiber composition, capillary architecture and luminal capillary. These seem to contribute to a change in morphology of muscle fibers. Therefore, we found out morphologically some characteristic features of muscle fibers with DM.
In diabetes mellitus various abnormalities were reported about muscle fibers, e.g. fiber composition, capillary architecture and luminal capillary. These seem to contribute to a change in morphology of muscle fibers. Therefore, we found out morphologically some characteristic features of muscle fibers with DM.
Purpose: The purpose is revealing some morphological characteristics of muscle fibers after diabetes mellitus (DM) rats (Goto-Kakizaki rats) engaged in aerobics activities.
Methods: Six male Goto-Kakizaki rats (6 weeks old) were divided into two groups, which were sedentary group (GK SED) and exercise group (GK EX). Six male wistar rats (6 weeks old) were also divided into the same way: WIS SED and WIS EX. The exercise groups were subjected to treadmill exercise, whose exercise was applied at sub-lactate threshold (sub-LT). Rats in the exercise group exercised for a period of 15 weeks, while rats in the sedentary group did not have a particular experimental condition. Fifteen weeks later, muscles (soleus) of all rats were then excised for histological and immunohistochemical analysis.
Results: Although soleus muscles of sedentary groups comprised both type I and type II fibers, soleus muscles of two-thirds of exercise groups (WIS EX and GK EX) contained only type I fibers. And type I fibers were bigger than type II fibers in the exercise groups with or without DM. Also, in regard to the number of capillaries around muscle fibers, type II had more than type I in WIS EX while type I had more than type II in GK EX. GLUT4 expression increased in GK SED and GK EX, but it did not differ in WIS SED and WIS EX.
Conclusion(s): The exercise at sub-LT marked a transition to type I fibers which have high oxidative capacity. That means skeletal muscle fibers change into ones which have high oxidative capacity, regardless of exercise intensity. And there was predominant GLUT4 expression of the transverse tubules (T-tubules) of soleus muscles in GK SED and GK EX. And GK SED and GK EX had a displacement of T-tubules in a longitudinal direction.
Implications: Muscle fibers of Goto-Kakizaki rats engaged in practice might shift their character to type I. Structural type of T-tubules, which is one of Ca2+ Release Units, was reported to convert easily depending on aging, inactivity and exercise. Moreover, the current study showed a lot of T-tubules in a longitudinal direction in muscle fibers of DM rats.
Funding acknowledgements: No funding
Topic: Professional practice: other
Ethics approval: The housing conditions and experimental protocols were approved by the Animal care and Ethics Use Committee of Saga University.
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