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Please use this identifier to cite or link to this item: http://hdl.handle.net/11375/24952
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dc.contributor.advisorMcClelland, Grant-
dc.contributor.authorCoulson, Soren-
dc.date.accessioned2019-10-03T19:57:37Z-
dc.date.available2019-10-03T19:57:37Z-
dc.date.issued2019-
dc.identifier.urihttp://hdl.handle.net/11375/24952-
dc.description.abstractHypoxia encountered at high altitude (HA) can limit energy production via aerobic metabolism in animals. Carbohydrate oxidation (CHO) has a greater ATP yield/mole O2 than fat oxidation, and HA-native deer mice show an increased reliance on CHO during submaximal exercise after hypoxia acclimation as an O2-saving strategy. However, hypoxia acclimation does not increase glycolytic capacity in muscle. We therefore tested the hypothesis that altered metabolic regulation of the CHO pathway allows HA mice to achieve higher rates of CHO during submaximal exercise. The objective of our study was to identify the effects of hypoxia acclimation on the regulation of two key proteins in the CHO pathway and their activation with exercise. Using first generation (G1) laboratory born and raised HA deer mice acclimated to normoxia or chronic hypoxia, we examined the metabolic regulation of muscle glucose uptake by glucose transporter (GLUT) 4 and of pyruvate oxidation by pyruvate dehydrogenase (PDH). The gastrocnemius was electrically stimulated in situ under anaesthesia and acute normoxia at two submaximal workloads relative to maximal force production, which was measured using a force transducer. In frozen gastrocnemius following stimulation or rest, GLUT4 protein content was measured via Western blotting of the sarcolemmal membrane fraction and PDH activity was measured using a radiolabelled assay. We found no differences in sarcolemmal GLUT4 content with stimulation, but PDH activity was increased in hypoxia, indicating increased rates of carbohydrate breakdown at similar workloads after acclimation. These data were compared to data from wild HA deer mice sampled at their native altitude. In support of our hypothesis, these data show that the metabolic regulation of the carbohydrate oxidative pathway changes with acclimation to support higher CHO rates during submaximal exercise. These data will help uncover the mechanistic underpinnings responsible for the exercise fuel use strategies observed exclusively in HA-native mice.en_US
dc.language.isoenen_US
dc.subjectHigh altitudeen_US
dc.subjectAdaptationen_US
dc.subjectDeer mouseen_US
dc.subjectMuscleen_US
dc.subjectMetabolismen_US
dc.subjectMetabolic regulationen_US
dc.titleChanges in metabolic regulation of the carbohydrate oxidative pathway in exercising high altitude deer miceen_US
dc.title.alternativeMetabolic regulation in exercising high altitude deer miceen_US
dc.typeThesisen_US
dc.contributor.departmentBiologyen_US
dc.description.degreetypeThesisen_US
dc.description.degreeMaster of Science (MSc)en_US
dc.description.layabstractAt high altitude, oxygen availability is low and can be challenging for active animals. Preferential carbohydrate oxidation is a metabolic strategy used by high altitude-native deer mice to fuel exercise because of its high energy yield per oxygen consumed. Despite the increase in carbohydrate breakdown, the capacity for muscles to use carbohydrates did not change, suggesting that the regulation of this metabolic pathway may be changing instead. We measured the contributions of two proteins involved in carbohydrate metabolism in active muscle, pyruvate dehydrogenase (PDH) and glucose transporter 4 (GLUT4), at different muscle workloads and after acclimation to high altitude conditions. We found no differences in GLUT4 content, but PDH activity was higher in hypoxia-acclimated mice at similar intensities, indicating increased rates of carbohydrate breakdown after acclimation. These data suggest that the regulation of the carbohydrate metabolic pathway changes with acclimation to support higher rates of carbohydrate oxidation during exercise.en_US
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