title: Critical role for free radicals on sprint exercise-induced CaMKII and AMPKα phosphorylation in human skeletal muscle.
abstract: The extremely high energy demand elicited by sprint exercise is satisfied by an increase in O2 consumption combined with a high glycolytic rate, leading to a marked lactate accumulation, increased AMP-to-ATP ratio, and reduced NAD(+)/NADH.H(+) and muscle pH, which are accompanied by marked Thr(172) AMP-activated protein kinase (AMPK)-α phosphorylation during the recovery period by a mechanism not fully understood. To determine the role played by reactive nitrogen and oxygen species (RNOS) on Thr(172)-AMPKα phosphorylation in response to cycling sprint exercise, nine voluntary participants performed a single 30-s sprint (Wingate test) on two occasions: one 2 h after the ingestion of placebo and another after the intake of antioxidants (α-lipoic acid, vitamin C, and vitamin E) in a double-blind design. Vastus lateralis muscle biopsies were obtained before, immediately postsprint, and 30 and 120 min postsprint. Performance and muscle metabolism were similar during both sprints. The NAD(+)-to-NADH.H(+) ratio was similarly reduced (84%) and the AMP-to-ATP ratio was similarly increased (×21-fold) immediately after the sprints. Thr(286) Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and Thr(172)-AMPKα phosphorylations were increased after the control sprint (with placebo) but not when the sprints were preceded by the ingestion of antioxidants. Ser(485)-AMPKα1/Ser(491)-AMPKα2 phosphorylation, a known inhibitory mechanism of Thr(172)-AMPKα phosphorylation, was increased only with antioxidant ingestion. In conclusion, RNOS play a crucial role in AMPK-mediated signaling after sprint exercise in human skeletal muscle. Antioxidant ingestion 2 h before sprint exercise abrogates the Thr(172)-AMPKα phosphorylation response observed after the ingestion of placebo by reducing CaMKII and increasing Ser(485)-AMPKα1/Ser(491)-AMPKα2 phosphorylation. Sprint performance, muscle metabolism, and AMP-to-ATP and NAD(+)-to-NADH.H(+) ratios are not affected by the acute ingestion of antioxidants.
authors.affiliation: Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira, Las Palmas de Gran Canaria 35017, Canary Island, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Morales-Alamo
authors.forename: Jesús Gustavo
authors.initials: JG
authors.lastname: Ponce-González
authors.forename: Amelia
authors.initials: A
authors.lastname: Guadalupe-Grau
authors.forename: Lorena
authors.initials: L
authors.lastname: Rodríguez-García
authors.forename: Alfredo
authors.initials: A
authors.lastname: Santana
authors.forename: Roser
authors.initials: R
authors.lastname: Cusso
authors.forename: Mario
authors.initials: M
authors.lastname: Guerrero
authors.forename: Cecilia
authors.initials: C
authors.lastname: Dorado
authors.forename: Borja
authors.initials: B
authors.lastname: Guerra
authors.forename: José A L
authors.initials: JA
authors.lastname: Calbet
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000328:Adult; D000975:Antioxidants / Q000378:metabolism; D001786:Blood Glucose / Q000378:metabolism; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism*; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D005609:Free Radicals / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000097:blood / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology*; D009243:NAD / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology; D010766:Phosphorylation; D026361:Reactive Nitrogen Species / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012119:Respiration
chemical_list: D000975:Antioxidants; D001786:Blood Glucose; D005609:Free Radicals; D007328:Insulin; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D009243:NAD; D019344:Lactic Acid; D000249:Adenosine Monophosphate; D000255:Adenosine Triphosphate; C526181:PRKAA2 protein, human; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D055372:AMP-Activated Protein Kinases; C526180:PRKAA1 protein, human