title: HSP72 gene expression progressively increases in human skeletal muscle during prolonged, exhaustive exercise.
abstract: To examine the effect of exercise on heat shock protein (HSP) 72 mRNA expression in skeletal muscle, five healthy humans (20 +/- 1 yr; 64 +/- 3 kg; peak O(2) uptake of 2.55 +/- 0.2 l/min) cycled until exhaustion at a workload corresponding to 63% peak O(2) uptake. Muscle was sampled from the vastus lateralis, and muscle temperature was measured at rest (R), 10 min of exercise (Min10), approximately 40 min before fatigue (F-40 = 144 +/- 7 min), and fatigue (F = 186 +/- 15 min). Muscle samples were analyzed for HSP72 mRNA expression, as well as glycogen and lactate concentration. Muscle temperature increased (P < 0.05) during the first 10 min of exercise but then remained constant for the duration of the exercise. Similarly, lactate concentration increased (P < 0.05) when Min10 was compared with R but decreased (P < 0.05) thereafter, such that concentrations at F-40 and F were not different from those at R. In contrast, muscle glycogen concentration fell progressively throughout exercise (486 +/- 74 vs. 25 +/- 7 mmol/kg dry weight for R and F, respectively; P < 0.05). HSP72 mRNA was detected at R but did not increase by Min10. However, HSP72 mRNA increased (P < 0.05) 2.2 +/- 0.5- and 2.6 +/- 0.9-fold, respectively, when F-40 and F were compared with R. These data demonstrate that HSP72 mRNA increases progressively during acute cycling, suggesting that processes that take place throughout concentric exercise are capable of initiating a stress response.
authors.affiliation: Exercise Physiology and Metabolism Laboratory, Department of Physiology, The University of Melbourne, Parkville, Victoria 3052, Australia. m.febbraio@physiology.unimelb.edu.au
authors.forename: M A
authors.initials: MA
authors.lastname: Febbraio
authors.forename: I
authors.initials: I
authors.lastname: Koukoulas
mesh_terms: D000328:Adult; D001642:Bicycling; D015444:Exercise / Q000502:physiology*; D015870:Gene Expression / Q000502:physiology*; D006003:Glycogen / Q000378:metabolism; D050884:HSP72 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000235:genetics*; D006706:Homeostasis; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism; D018482:Muscle, Skeletal / Q000502:physiology*; D010807:Physical Endurance; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors
chemical_list: D050884:HSP72 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D012333:RNA, Messenger; D019344:Lactic Acid; D006003:Glycogen