Phosphorylase kinase (PhK), a key regulator of glycogenolysis, is critical for maintaining blood glucose levels thus providing energy to sustain muscle contraction. A deficiency of PhK in skeletal muscle is the cause of one type of glycogen storage disease (GSD) in humans. This study investigates the physiological and genetic adaptations that occur in a mouse model of GSD, I/LnJ mice, in response to voluntary exercise. Juvenile (6-8 weeks old) and adult (12-14 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, total running time, total running distance, and average speed. After five weeks, adult and juvenile I/LnJ mice were running 45-70% of the daily distance of age-matched, wild-type mice. A training effect was observed in wild-type mice during the five week exercise period, but no significant difference was observed in heart/body weight ratios in exercised mice compared to non-exercised controls. Expression levels of glucose transporter 4 (GLUT4), pyruvate dehydrogenase (PDHA1), and phosphofructokinase (PFKM) as a result of exercise were determined by quantitative RT-PCR in both I/LnJ and ii C57/Bl6 mice. No significant differences in expression levels were found between mouse strains. Our long term goal is to gain insights into the I/LnJ strain’s PhK deficiency in order to better understand human GSDs.
Advisor(s) or Committee Chair
Dr. Nancy Rice
Physical Sciences and Mathematics
Mefford, Ashley M., "Voluntary Exercise in Phosphorylase Kinase Deficient Mice" (2010). Honors College Capstone Experience/Thesis Projects. Paper 238.