Virginia Tech
    • Log in
    View Item 
    •   VTechWorks Home
    • ETDs: Virginia Tech Electronic Theses and Dissertations
    • Doctoral Dissertations
    • View Item
    •   VTechWorks Home
    • ETDs: Virginia Tech Electronic Theses and Dissertations
    • Doctoral Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Postmortem metabolism in porcine skeletal muscle

    Thumbnail
    View/Open
    England_EM_D_2015.pdf (1.278Mb)
    Downloads: 3336
    Supporting documents (93.66Kb)
    Downloads: 85
    Date
    2015-07-21
    Author
    England, Eric M.
    Metadata
    Show full item record
    Abstract
    Once an animal is harvested for meat, skeletal muscle attempts to maintain ATP at or near antemortem levels. To maintain ATP levels postmortem, stored glycogen is catabolized to produce ATP through glycolysis and possibly oxidative metabolism. Hydrolysis of the produced ATP acidifies muscle until an ultimate pH is reached. The ultimate pH of meat directly impacts the quality characteristics of color, texture, and water holding capacity. Therefore, our research intends to describe the contributions glycolysis and oxidative metabolism play in determining ultimate pH and fresh meat quality. Traditionally, glycogen content at death was thought to be responsible for dictating ultimate pH. This was especially true in oxidative muscle with limited glycogen stores. Yet, our research indicated that in the presence of excess glycogen, oxidative muscle maintains a high ultimate pH. Rather, pH inactivation of phosphofructokinase is responsible for terminating postmortem glycolysis and brackets ultimate pH between 5.9 – 5.5. Meat with a pH below this range is uncommon. However, AMPK γ3R200Q mutant pigs produce meat with an ultimate pH near 5.3. Due to lower AMP deaminase abundance in their muscle, AMP levels are elevated late postmortem. Because AMP is a potent activator of phosphofructokinase, the aberrant meat quality from AMPK γ3R200Q mutant pigs is caused by extended postmortem glycolysis. Combined, these data further our understanding of the factors that contribute to the formation of fresh meat quality. We also characterized AMPK γ3R200Q muscle by investigating antemortem skeletal muscle lactate transport. Lactate is transported in or out of tissues by proton-linked iii monocarboxylate transporters (MCTs). Previous reports indicated that acute activation of AMPK increased monocarboxylate transporter expression in skeletal muscle of other species. Yet, it was unknown the impact chronic activation of AMPK will have on MCT1, MCT2, and MCT4 expression in pigs. Compared to wild-type pigs, the longissimus lumborum of AMPK γ3R200Q pigs increased both MCT2 and MCT4 protein expression. Our data suggest glycolytic skeletal muscle from the AMPK γ3R200Q pigs has increased capacity for antemortem lactate export from muscle and possibly increased pyruvate transport into the mitochondria.
    URI
    http://hdl.handle.net/10919/54580
    Collections
    • Doctoral Dissertations [16868]

    If you believe that any material in VTechWorks should be removed, please see our policy and procedure for Requesting that Material be Amended or Removed. All takedown requests will be promptly acknowledged and investigated.

    Virginia Tech | University Libraries | Contact Us
     

     

    VTechWorks

    AboutPoliciesHelp

    Browse

    All of VTechWorksCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

    My Account

    Log inRegister

    Statistics

    View Usage Statistics

    If you believe that any material in VTechWorks should be removed, please see our policy and procedure for Requesting that Material be Amended or Removed. All takedown requests will be promptly acknowledged and investigated.

    Virginia Tech | University Libraries | Contact Us