Relationships between muscle membrane lipids, fiber type, and enzyme activities in sedentary and exercised rats
| Autor: | J. F. Y. Hoh, Gregory J. Cooney, David A. Pan, Louise A. Baur, A. B. Jenkins, Leonard H Storlien, A. D. Kriketos, J. R. Sutton |
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| Rok vydání: | 1995 |
| Předmět: |
Male
medicine.medical_specialty Physiology Muscle Fibers Skeletal Physical Exertion Citrate (si)-Synthase Extensor digitorum longus muscle Membrane Lipids Insulin resistance Physiology (medical) Internal medicine Hexokinase Physical Conditioning Animal medicine Citrate synthase Animals Glycolysis Rats Wistar Muscle Skeletal chemistry.chemical_classification Soleus muscle biology Fatty Acids Fatty acid Skeletal muscle medicine.disease Hindlimb Rats medicine.anatomical_structure Endocrinology chemistry Biochemistry biology.protein Female Oxidation-Reduction Polyunsaturated fatty acid |
| Zdroj: | The American journal of physiology. 269(5 Pt 2) |
| ISSN: | 0002-9513 |
| Popis: | Insulin resistance in skeletal muscle is associated with 1) relative increases in the proportion of glycolytic and fast-twitch muscle fibers and decreases in the proportion of more oxidative fibers and 2) a higher proportion of the saturated fatty acids in membrane structural lipids. Exercise is known to improve insulin action. The aims of the current studies were 1) to investigate the relationship between muscle fiber type and membrane fatty acid composition and 2) to determine how voluntary exercise might influence both variables. In sedentary Wistar rats in experiment 1, increased amounts of unsaturated fatty acids were found in the more oxidative insulin-sensitive red quadriceps and soleus muscles, whereas reduced levels of polyunsaturated fatty acids were found in primarily glycolytic white quadriceps muscles. In experiment 2, voluntary running-wheel exercise by adult female rats over 45 days resulted in reduced proportions of type IIb fibers (P = 0.01) and increased proportions of type IIa/IIx fibers (P = 0.03) in extensor digitorum longus muscle. The magnitude of these changes was related to the distance run (r = -0.73, P = 0.04; r = 0.79, P = 0.02, respectively). Exercise significantly increased oxidative capacity, as assessed by the proportion of intensely NADH-stained fibers (P = 0.0004) and citrate synthase (P = 0.003) and hexokinase (P = 0.04) activities. Citrate synthase activity was also increased by exercise in soleus muscle, where, as expected, no fiber type changes were detected. No significant differences in the fatty acid profile of soleus and extensor digitorum longus were found between groups.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: | OpenAIRE |
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