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Muscle Adaptation in Response to Voluntary Exercise in Phosphorylase Kinase Deficient Mice
Author(s) -
Mefford Ashley M,
Rice Nancy A.
Publication year - 2009
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.23.1_supplement.506.10
Subject(s) - glycogenolysis , glut4 , medicine , endocrinology , phosphofructokinase , glycogen , glycogen phosphorylase , glucose transporter , physical exercise , turnover , biology , glycolysis , insulin , metabolism , management , economics
Phosphorylase kinase (PhK), the key regulator of glycogenolysis, is responsible for maintaining blood glucose levels thus providing energy to sustain muscle contraction. A deficiency of PhK is the cause of glycogen storage disease (GSD) type IX in humans. This study investigates the physiological and genetic adaptations that occur in a mouse model of GSD (I/LnJ) in response to voluntary exercise. Juvenile (4‐6 weeks old) I/LnJ and wild‐type C57/Bl6 mice exercised voluntarily for 1, 2 or 5 weeks. Exercise data was calculated as mean daily running time, daily running distance, and average speed. At week 5, I/LnJ mice ran approximately 7.1 km/day, whereas C57/Bl6 mice ran twice as long, 14.9 km/day. The average running speed for I/LnJ mice, 32.1 m/min, was significantly lower than C57/Bl6 mice whose average speed was 38.4 m/min. While a significant training effect was observed in both mouse strains during the 5 week exercise period, no significant difference was observed in heart/body weight ratios in exercised mice compared to non‐exercised controls. Changes in gene expression of glucose transporter 4 (GLUT4), pyruvate dehydrogenase (PDHA1), and phosphofructokinase (PFKM) as a result of exercise have been determined by quantitative RT‐PCR in both I/LnJ and C57/Bl6 mice and indicate genetic factors correlate with the observed physiological changes. It is our long‐term goal to determine dietary and exercise therapies that can be translated to humans patients with GSD. This work was supported by the National Institute of Health grant 2PORR16481 (NAR) and a WKU Faculty Scholarship (NAR).