Related Experiment Video
Updated: Jun 27, 2026

Application of Chronic Stimulation to Study Contractile Activity-induced Rat Skeletal Muscle Phenotypic Adaptations
Published on: January 25, 2018
Different adaptations of alpha-actinin isoforms to exercise training in rat skeletal muscles
1Department of Physiology, St Marianna University School of Medicine, Kanagawa, Japan.
Aim:
Alpha (alpha)-actinins are located in the skeletal muscle Z-line and form actin-actin cross-links. Mammalian skeletal muscle has two isoforms: alpha-actinin-2 and alpha-actinin-3. However, the response of alpha-actinin to exercise training is little understood. Therefore, the current study examined the effects of exercise training on the expression level of two alpha-actinin isoforms in skeletal muscles.
Methods:
Twelve male Wistar rats were assigned randomly to a control (C; n = 6) or exercise training (T; n = 6) group. After T animals were trained on an animal treadmill for 9 weeks, alpha-actinin-2 and alpha-actinin-3 levels in the plantaris, white and red gastrocnemius muscles were analysed. In addition, changes in the myosin heavy chain (MyHC) composition were assessed, and muscle bioenergetic enzyme activities were measured.
Results:
Results show that exercise training increased alpha-actinin-2 expression levels in all muscles (P < 0.05). However, no significant difference was found in alpha-actinin-3 expression levels between C and T animals. Subsequent MyHC analyses of all muscle showed an MyHC shift with direction from IIb to IIa. Furthermore, enzymatic analysis revealed that exercise training improved enzyme activities related to aerobic metabolism.
Conclusion:
The results of this study demonstrate that exercise training alters the expression level of alpha-actinin at the isoform level. Moreover, the increase in expression levels of alpha-actinin-2 is apparently related to alteration of skeletal muscle: its aerobic capacity is improved.
More Related Videos
07:44Construction of Constant-Load (Isotonic) and Constant-Velocity (Isokinetic) Torque-Velocity-Power Profiles In vivo for the Rat Plantar Flexors
Published on: October 3, 2025
08:12Intact Short, Intermediate, and Long Skeletal Muscle Fibers Obtained by Enzymatic Dissociation of Six Hindlimb Muscles of Mice: Beyond Flexor Digitorum Brevis
Published on: December 1, 2023
Related Concept Videos
Introduction to Actin
Cellular Adaptation II: Hypertrophy
Actin Polymerization and Cell Motility
Actin cytoskeleton dynamics can produce pushing, pulling, and resistance forces that help the cell to migrate.
Exercise and Muscle Performance
Endurance exercises
Endurance exercises involve running, swimming, or cycling, which require repetitive movements with low force output. When a person engages in endurance exercise, a few noticeable changes occur in their skeletal muscles. For instance, the number of capillaries...
Actin and Myosin in Muscle Contraction
Adaptability of Cytoskeletal Filaments