dc.contributor.author	Lees, Simon J.	en
dc.contributor.committeechair	Williams, Jay H.	en
dc.contributor.committeemember	Talmadge, Robert	en
dc.contributor.committeemember	Newton, William E.	en
dc.contributor.department	Human Nutrition, Foods, and Exercise	en
dc.date.accessioned	2014-03-14T20:47:05Z	en
dc.date.adate	2000-11-06	en
dc.date.available	2014-03-14T20:47:05Z	en
dc.date.issued	2000-10-13	en
dc.date.rdate	2001-11-06	en
dc.date.sdate	2000-10-27	en
dc.description.abstract	Skeletal muscle fatigue can be defined as the inability to produce a desired amount of force. Fatigue can not only limit athletic performance and rehabilitation, but it can affect one's ability to perform every day activity as well. Despite extensive investigation of muscle fatigue, little is known about the exact mechanisms that result in decreased muscle performance. It likely involves several factors that are themselves dependent upon activation patterns and intensity. The process of excitation-contraction (EC) coupling is of particular importance with respect to regulation of force production. The release of calcium (Ca²⁺) from the sarcoplasmic reticulum (SR), which is stimulated by the depolarization of the sarcolemma, causes muscle contraction. The SR Ca²⁺-adenosine triphosphatase (ATPase) drives the translocation of two Ca²⁺ ions into the SR, utilizing the energy derived from the hydrolysis of one adenosine triphosphate (ATP) molecule. The process of SR Ca²⁺ uptake causes muscle relaxation. It has been proposed that both glycogen and glycolytic enzymes are associated with the SR membrane (SR-glycogenolytic complex). Interestingly, glycogen phosphorylase, an enzyme involved in glycogen breakdown, seems to be associated with the SR-glycogenolytic complex through its binding to glycogen. The presence of the SR-glycogenolytic system may serve to locally regenerate ATP utilized by the SR Ca²⁺-ATPase. The purpose of the present study was to investigate the effects of prolonged muscle contraction on glycogen concentration, glycogen phosphorylase content and activity, and maximum Ca²⁺ uptake rate associated with the SR. Tetanic contractions, elicited once per second for 15 minutes, significantly reduced glycogen associated with SR to 5.1% of control from 401.17 ± 79.81 to 20.46 ± 2.16 mg/mg SR protein (£ 0.05). The optical density of glycogen phosphorylase from SDS-PAGE was significantly reduced to 21.2% of control (£ 0.05). Activity of glycogen phosphorylase, in the direction of glycogen breakdown, was significantly reduced to 4.1% of control (£ 0.05). Pyridoxal 5'-phosphate (PLP) concentration, a quantitative indicator of glycogen phosphorylase content, was significantly reduced to 3.3% of control (£ 0.05). Maximum SR Ca²⁺ uptake rates were significantly reduced to 80.8% of control (£ 0.05). These data suggest reduced glycogen and glycogen phosphorylase may be involved, either directly or indirectly, in a mechanism that causes decreased SR Ca²⁺ uptake normally found in fatigue.	en
dc.description.degree	Master of Science	en
dc.identifier.other	etd-10272000-09390032	en
dc.identifier.sourceurl	http://scholar.lib.vt.edu/theses/available/etd-10272000-09390032/	en
dc.identifier.uri	http://hdl.handle.net/10919/35506	en
dc.publisher	Virginia Tech	en
dc.relation.haspart	88-108.pdf	en
dc.relation.haspart	1-38.pdf1.pdf	en
dc.relation.haspart	39-65.pdf	en
dc.relation.haspart	66-87.pdf	en
dc.rights	In Copyright	en
dc.rights.uri	http://rightsstatements.org/vocab/InC/1.0/	en
dc.subject	skeletal muscle	en
dc.subject	sarcoplasmic reticulum	en
dc.subject	Fatigue	en
dc.subject	calcium uptake	en
dc.title	The effects of fatigue on glycogen, glycogen phosphorylase, and calcium uptake associated with the sarcoplasmic reticulum of rat skeletal muscle	en
dc.type	Thesis	en
thesis.degree.discipline	Human Nutrition, Foods, and Exercise	en
thesis.degree.grantor	Virginia Polytechnic Institute and State University	en
thesis.degree.level	masters	en
thesis.degree.name	Master of Science	en

The effects of fatigue on glycogen, glycogen phosphorylase, and calcium uptake associated with the sarcoplasmic reticulum of rat skeletal muscle

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