{"id":{"repo_id":"vu-aus","oai_identifier":"oai:eprints.vu.edu.au:19414"},"canonical_url":"https://search.dev.ndltd.org/etd/vu-aus/oai:eprints.vu.edu.au:19414","repository":{"repo_id":"vu-aus","name":"Victoria University (Australia)","base_url":"https://vuir.vu.edu.au/cgi/oai2"},"display":{"title":"Alkalosis and digoxin effects on plasma potassium, ionic homeostasis and exercise performance in healthy humans","abstract":"Muscle contractions induce cellular potassium (K+) efflux which may contribute to impaired muscle cell membrane excitability and fatigue. The magnitude of K+ changes are dependent on the size of contracting muscle mass, duration and intensity of exercise, and health and fitness status of participants. Activation of the sarcolemmal and t-tubular bound sodium-potassium adenosine 5’ triphosphatase enzyme (Na+,K+ATPase, NKA) mediates muscle cell K+ and Na+ active exchange, and is instrumental in the maintenance of muscle cellular and plasma K+ homeostasis during exercise. Therefore modulations of NKA function might enhance or impair exercise induced K+ disturbances, and theoretically can have a profound effect on muscle excitability and exercise performance. This thesis examined the effects of two interventions designed to induce acute or short term upregulation and downregulation of NKA activity on K+ homeostasis and exercise performance in healthy humans. Study 1 investigated the effects of metabolically induced alkalosis on plasma K+ regulation during submaximal finger flexion (small muscle mass) contractions and fatigue in healthy humans. Study 2 investigated the effects of a clinically relevant dose of digoxin administration on K+ regulation, during intermittent supramaximal finger flexion contractions (small muscle mass) and fatigue in healthy humans. Study 3 investigated the effects of digoxin on K+ regulation during progressive increasing intensity submaximal leg cycling exercise (large muscle mass) and fatigue in the same healthy participants as in study 2. A secondary focus of this thesis was to examine the ionic, metabolic and acid-base disturbances during small and large muscle mass exercise and in recovery. This included the regulatory role of NKA in active (study 1 and 2) and inactive tissue (study 3), during small (study 1 and 2) and large (study 3) muscle mass exercise.","abstract_html":"Muscle contractions induce cellular potassium (K+) efflux which may contribute to impaired muscle cell membrane excitability and fatigue. The magnitude of K+ changes are dependent on the size of contracting muscle mass, duration and intensity of exercise, and health and fitness status of participants. Activation of the sarcolemmal and t-tubular bound sodium-potassium adenosine 5’ triphosphatase enzyme (Na+,K+ATPase, NKA) mediates muscle cell K+ and Na+ active exchange, and is instrumental in the maintenance of muscle cellular and plasma K+ homeostasis during exercise. Therefore modulations of NKA function might enhance or impair exercise induced K+ disturbances, and theoretically can have a profound effect on muscle excitability and exercise performance. This thesis examined the effects of two interventions designed to induce acute or short term upregulation and downregulation of NKA activity on K+ homeostasis and exercise performance in healthy humans. Study 1 investigated the effects of metabolically induced alkalosis on plasma K+ regulation during submaximal finger flexion (small muscle mass) contractions and fatigue in healthy humans. Study 2 investigated the effects of a clinically relevant dose of digoxin administration on K+ regulation, during intermittent supramaximal finger flexion contractions (small muscle mass) and fatigue in healthy humans. Study 3 investigated the effects of digoxin on K+ regulation during progressive increasing intensity submaximal leg cycling exercise (large muscle mass) and fatigue in the same healthy participants as in study 2. A secondary focus of this thesis was to examine the ionic, metabolic and acid-base disturbances during small and large muscle mass exercise and in recovery. This included the regulatory role of NKA in active (study 1 and 2) and inactive tissue (study 3), during small (study 1 and 2) and large (study 3) muscle mass exercise.","abstract_has_math":false,"creators":["Sostaric, Simon"],"institution":"Victoria University","degree_name":"phd","degree_level":"doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2012,"date_issued":"2012","date_published":"2012","updated_at":"2026-07-24T06:33:28Z","subjects":["1101 Medical Biochemistry and Metabolomics","1102 Cardiorespiratory Medicine and Haematology","1106 Human Movement and Sports Science","School of Sport and Exercise Science"],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Sostaric, Simon"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2012"]},{"key":"dc:date.issued","label":"Date","values":["2012"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["School of Sport & Exercise Science"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["Victoria University"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://vuir.vu.edu.au/19414/"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["phd"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["1101 Medical Biochemistry and Metabolomics","1102 Cardiorespiratory Medicine and Haematology","1106 Human Movement and Sports Science","School of Sport and Exercise Science"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://vuir.vu.edu.au/19414/1/Simon_Sostarik.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Muscle contractions induce cellular potassium (K+) efflux which may contribute to impaired muscle cell membrane excitability and fatigue. The magnitude of K+ changes are dependent on the size of contracting muscle mass, duration and intensity of exercise, and health and fitness status of participants. Activation of the sarcolemmal and t-tubular bound sodium-potassium adenosine 5’ triphosphatase enzyme (Na+,K+ATPase, NKA) mediates muscle cell K+ and Na+ active exchange, and is instrumental in the maintenance of muscle cellular and plasma K+ homeostasis during exercise. Therefore modulations of NKA function might enhance or impair exercise induced K+ disturbances, and theoretically can have a profound effect on muscle excitability and exercise performance. This thesis examined the effects of two interventions designed to induce acute or short term upregulation and downregulation of NKA activity on K+ homeostasis and exercise performance in healthy humans. Study 1 investigated the effects of metabolically induced alkalosis on plasma K+ regulation during submaximal finger flexion (small muscle mass) contractions and fatigue in healthy humans. Study 2 investigated the effects of a clinically relevant dose of digoxin administration on K+ regulation, during intermittent supramaximal finger flexion contractions (small muscle mass) and fatigue in healthy humans. Study 3 investigated the effects of digoxin on K+ regulation during progressive increasing intensity submaximal leg cycling exercise (large muscle mass) and fatigue in the same healthy participants as in study 2. A secondary focus of this thesis was to examine the ionic, metabolic and acid-base disturbances during small and large muscle mass exercise and in recovery. This included the regulatory role of NKA in active (study 1 and 2) and inactive tissue (study 3), during small (study 1 and 2) and large (study 3) muscle mass exercise."]},{"key":"dc:format","label":"Dc Format","values":["text"]},{"key":"dc:title","label":"Title","values":["Alkalosis and digoxin effects on plasma potassium, ionic homeostasis and exercise performance in healthy humans"]}]}],"canonical_facts":{"dc:creator":["Sostaric, Simon"],"dc:date":["2012"],"dc:date.issued":["2012"],"dc:description.abstract":["Muscle contractions induce cellular potassium (K+) efflux which may contribute to impaired muscle cell membrane excitability and fatigue. The magnitude of K+ changes are dependent on the size of contracting muscle mass, duration and intensity of exercise, and health and fitness status of participants. Activation of the sarcolemmal and t-tubular bound sodium-potassium adenosine 5’ triphosphatase enzyme (Na+,K+ATPase, NKA) mediates muscle cell K+ and Na+ active exchange, and is instrumental in the maintenance of muscle cellular and plasma K+ homeostasis during exercise. Therefore modulations of NKA function might enhance or impair exercise induced K+ disturbances, and theoretically can have a profound effect on muscle excitability and exercise performance. This thesis examined the effects of two interventions designed to induce acute or short term upregulation and downregulation of NKA activity on K+ homeostasis and exercise performance in healthy humans. Study 1 investigated the effects of metabolically induced alkalosis on plasma K+ regulation during submaximal finger flexion (small muscle mass) contractions and fatigue in healthy humans. Study 2 investigated the effects of a clinically relevant dose of digoxin administration on K+ regulation, during intermittent supramaximal finger flexion contractions (small muscle mass) and fatigue in healthy humans. Study 3 investigated the effects of digoxin on K+ regulation during progressive increasing intensity submaximal leg cycling exercise (large muscle mass) and fatigue in the same healthy participants as in study 2. A secondary focus of this thesis was to examine the ionic, metabolic and acid-base disturbances during small and large muscle mass exercise and in recovery. This included the regulatory role of NKA in active (study 1 and 2) and inactive tissue (study 3), during small (study 1 and 2) and large (study 3) muscle mass exercise."],"dc:format":["text"],"dc:identifier.uri":["https://vuir.vu.edu.au/19414/1/Simon_Sostarik.pdf"],"dc:language":["en"],"dc:publisher.department":["School of Sport & Exercise Science"],"dc:publisher.institution":["Victoria University"],"dc:relation.isreferencedby":["https://vuir.vu.edu.au/19414/"],"dc:subject":["1101 Medical Biochemistry and Metabolomics","1102 Cardiorespiratory Medicine and Haematology","1106 Human Movement and Sports Science","School of Sport and Exercise Science"],"dc:title":["Alkalosis and digoxin effects on plasma potassium, ionic homeostasis and exercise performance in healthy humans"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["doctoral"],"dc:type.qualificationname":["phd"]},"updated_at":"2026-07-24T06:33:28Z"}