The <i>phka</i>1 deficient I/LnJ mouse exhibits endurance exercise deficiency with no compensatory changes in glycolytic gene expression

• 作者: Ashley M. Mefford Claci C. Ayers Nancy A. Rice Naomi S. Rowland
• 来源期刊: 分子和综合生理学期刊(英文)
• 学科: 医学
• 关键词: PHOSPHORYLASE Kinase GLYCOGEN Storage Disease Exercise Skeletal Muscle I/LnJ
• 年，卷（期）: 2013,（2）
• 页码范围: 87-94
• 页数: 8页
• 分类号: R73

摘要

During exercise, phosphorylase kinase (PhK) is the key regulatory enzyme responsible for maintaining glycogenolytic flux to sustain muscle contraction. The absence of PhK in skeletal muscle results in glycogen storage disease (GSD) Type IX which is characterized by muscle weakness and rapid fatigue upon exercise. In this study, we have used the phka1 deficient I/LnJ mouse model of GSD to investigate the physiological and genetic adaptations that occur in response to voluntary exercise. When quantified over training periods of either 1, 2, or 5 weeks, I/LnJ mice ran significantly less time/day and distance/day than agematched C57/Bl6 mice. Cumulatively after five weeks, adult I/LnJ mice ran ~1/2 the total time and distance of wild-type mice, 116 ± 6 hours and 211 ±23 kmversus 194 ± 3 hours and 418 ±4 km, respectively. After 5 weeks, C57/Bl6 mice demonstrated an increase in endurance as a result of aerobic training;this observed physiological adaptation was not present in I/LnJ mice. The decrease in total distance run by I/LnJ mice was not due to a reduction in speed;juvenile and adult I/LnJ mice ran ~75% - 80% as fast as C57/Bl6 mice. When transcription of glycolytic genes glucose transporter 4 (scla1), pyruvate dehydrogenase (pdha1), and phosphofructokinase (pfk) were quantified at the end of each training period, no significant differences in expression levels were found between mouse strains, suggesting that non-glycolytic mechanisms work to maintain the muscle function observed in the I/LnJ mice.