title: Effects of graded exercise-induced dehydration and rehydration on circulatory markers of oxidative stress across the resting and exercising human leg.
abstract: Exercise in the heat enhances oxidative stress markers in the human circulation, but the contribution of active skeletal muscle and the influence of hydration status remain unknown. To address this question, we measured leg exchange of glutathione (GSH), glutathione disulfide (GSSG), superoxide dismutase activity (SOD) and isoprostanes in seven males at rest and during submaximal one-legged knee extensor exercise in the following four conditions: (1) control euhydration (0% reduction in body mass), (2) mild-dehydration (2%), (3) moderate-dehydration (3.5%), (4) rehydration (0%). In all resting and control exercise conditions, a net GSH uptake was observed across the leg. In contrast, a significant leg release of GSH into the circulation (-354 ± 221 μmol/min, P < 0.05) was observed during exercise with moderate-dehydration, which was still present following full rehydration (-206 ± 122 μmol/min, P < 0.05). During exercise, mild and moderate-dehydration decreased both femoral venous erythrocyte SOD activity (195 ± 6 vs. 180 ± 5 U/L, P < 0.05) and plasma isoprostanes (30 ± 1.1 vs. 25.9 ± 1.3 pg/L, P < 0.05), but during rehydration these were not different from control. In conclusion, these findings suggest that active skeletal muscles release GSH into the circulation under moderate dehydration and subsequent rehydration, possibly to enhance the antioxidant defense.
authors.affiliation: Centre for Sports Medicine and Human Performance, Brunel University, Uxbridge, Middlesex UB8 3PH, UK. Orlando.Laitano@univasf.edu.br
authors.forename: Orlando
authors.initials: O
authors.lastname: Laitano
authors.forename: Kameljit Kaur
authors.initials: KK
authors.lastname: Kalsi
authors.forename: James
authors.initials: J
authors.lastname: Pearson
authors.forename: Makra
authors.initials: M
authors.lastname: Lotlikar
authors.forename: Alvaro
authors.initials: A
authors.lastname: Reischak-Oliveira
authors.forename: José
authors.initials: J
authors.lastname: González-Alonso
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D015415:Biomarkers / Q000097:blood; D001835:Body Weight / Q000502:physiology; D003681:Dehydration / Q000378:metabolism*; D015444:Exercise / Q000502:physiology*; D005081:Exercise Therapy; D005440:Fluid Therapy; D005978:Glutathione / Q000097:blood; D019803:Glutathione Disulfide / Q000097:blood; D006801:Humans; D028421:Isoprostanes / Q000097:blood; D007866:Leg / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology*; D012039:Regional Blood Flow; D013482:Superoxide Dismutase / Q000097:blood; D055815:Young Adult
chemical_list: D000975:Antioxidants; D015415:Biomarkers; D028421:Isoprostanes; D013482:Superoxide Dismutase; D005978:Glutathione; D019803:Glutathione Disulfide