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Oxidative Gene Expression in Single Muscle Fibres after Continuous and Intermittent Exercise
Author(s) -
WANG LI,
Sahlin Kent
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.lb639
Subject(s) - pdk4 , endocrinology , medicine , oxidative phosphorylation , messenger rna , skeletal muscle , gene expression , coactivator , chemistry , basal (medicine) , glycolysis , biology , gene , metabolism , biochemistry , transcription factor , diabetes mellitus
Fibre‐type heterogeneity is a potential problem in the interpretation of gene expression in mixed muscle. The current study aimed to investigate the fibre‐type variation of master genes involved in oxidative metabolism and signaling pathway as well as the influence of exercise. Untrained subjects (n = 8) cycled for 90 min either at a constant 60 % of VO 2max (CE) or at an intensity alternating between 120 % (12 s) and 20 % of VO 2max (18 s) (IE). Muscle biopsies were obtained before (Pre) and 3 h after (Post) exercise. Peroxisome proliferator‐activated receptor‐γ coactivator‐1α (PGC‐1α) and pyruvate dehydrogenase kinase 4 (PDK4) genes were measured with quantitative real‐time PCR in freeze‐dried muscle single type I or type II fibres. PGC‐1α mRNA showed large variation within the same fibre type (> 3‐fold). PGC‐1α and PDK4 mRNA was 2–3‐fold higher in type I fibres (P < 0.05 vs. type II) at Pre, but at Post the difference was reduced (IE) or abolished (CE). Acute cycling increased PGC‐1α and PDK4 mRNA in both fibre types. Exercise‐induced increases in mRNA of PGC‐1α and PDK4 were negatively correlated with the basal level. We conclude that human skeletal muscle has higher baseline mRNA level of oxidative genes in type I than in type II fibres, but this difference is reduced after exercise. This may in part be explained by the negative correlation between the basal mRNA level and the exercise‐induced increase in mRNA . This work was supported by grants from the Swedish Research Council (23998‐50466), GIH and the National Centre for Research in Sports (CIF).