Glycogen extraction from skeletal muscle sarcoplasmic reticulum: structural and functional implications

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dc.contributor.authorLees, Simon J.en
dc.contributor.committeechairWilliams, Jay H.en
dc.contributor.committeememberWard, Christopher W.en
dc.contributor.committeememberNewton, William E.en
dc.contributor.committeememberBarbeau, William E.en
dc.contributor.committeememberMoore, David M.en
dc.contributor.departmentHuman Nutrition, Foods, and Exerciseen
dc.date.accessioned2014-03-14T20:08:39Zen
dc.date.adate2003-04-04en
dc.date.available2014-03-14T20:08:39Zen
dc.date.issued2003-03-27en
dc.date.rdate2007-04-04en
dc.date.sdate2003-03-31en
dc.description.abstractIn this investigation, skeletal muscle sarcoplasmic reticulum (SR) was purified from female Sprague Dawley rats (200-250 g). SR samples were subjected to two different biochemical glycogen-extraction protocols. The results suggest that both amylase and removal of EDTA (No-EDTA) from the homogenization and storage buffers reduced the amount of glycogen associated with the SR. Both of these treatments failed to impair SR calcium (Ca2+) handling when assayed under conditions where exogenous ATP was added and utilized for SR Ca2+ transport. In fact, these treatments seemed to cause a small increase in both SR Ca2+-uptake and release rates under these assay conditions. As expected, glycogen phosphorylase content was reduced as a result of glycogen extraction in the presence of amylase, however this was not the case for No-EDTA samples. Interestingly, many other proteins differed in content after glycogen extraction. These treatments resulted in a greater recovery of the sarco(endo)plasmic reticulum Ca2+ adenosine triphosphatase (SERCA) and a substantial loss of glycogen phosphorylase and glycogen debranching enzyme (AGL) in amylase-treated samples. Creatine kinase (CK) and pyruvate kinase (PK) contents were increased as a result of both glycogen-extraction conditions. It was imperative to consider these altered protein contents while analyzing the data and assessing the effects of glycogen extraction on SR Ca2+ handling. After normalizing to SERCA content, only No-EDTA samples had higher adenosine triphosphate (ATP)-supported SR Ca2+-uptake rates compared to control samples. For endogenously synthesized ATP-supported SR Ca2+-uptake experiments, normalizing data to protein content (either CK and SERCA or PK and SERCA) revealed that amylase-treated samples had lower SR Ca2+-uptake rates, compared to control samples. Although not significant, SR Ca2+-uptake rates for No-EDTA samples were also lower than control samples. These data suggest that changes in endogenously supported SR Ca2+-uptake due to glycogen extraction affected the source of ATP synthesis (either PK or CK), the effectiveness of energy utilization for Ca2+ transport (SERCA), or altered the metabolic channeling properties.en
dc.description.degreePh. D.en
dc.identifier.otheretd-03312003-141236en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-03312003-141236/en
dc.identifier.urihttp://hdl.handle.net/10919/26566en
dc.publisherVirginia Techen
dc.relation.haspartSimonLees.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectskeletal muscleen
dc.subjectglycogenen
dc.subjectsarcoplasmic reticulumen
dc.subjectcalcium handlingen
dc.titleGlycogen extraction from skeletal muscle sarcoplasmic reticulum: structural and functional implicationsen
dc.typeDissertationen
thesis.degree.disciplineHuman Nutrition, Foods, and Exerciseen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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