title: Exercise-induced metallothionein expression in human skeletal muscle fibres.
abstract: Exercise induces free oxygen radicals that cause oxidative stress, and metallothioneins (MTs) are increased in states of oxidative stress and possess anti-apoptotic effects. We therefore studied expression of the antioxidant factors metallothionein I and II (MT-I + II) in muscle biopsies obtained in response to 3 h of bicycle exercise performed by healthy men and in resting controls. Both MT-I + II proteins and MT-II mRNA expression increased significantly in both type I and II muscle fibres after exercise. Moreover, 24 h after exercise the levels of MT-II mRNA and MT-I + II proteins were still highly increased and the MT-II mRNA expression reached a 15-fold increase. As expected, immunohistochemical detection of malondialdehyde (MDA) and nitrotyrosine (NITT) showed that formation of free radicals and oxidative stress were clearly increased in exercising muscle peaking shortly after the end of exercise in both type I and II muscle fibres. This is the first report demonstrating that MT-I + II are significantly induced in human skeletal muscle fibres following exercise. As MT-I + II are antioxidant factors that protect various tissues during pathological conditions, the MT-I + II increases post exercise may represent a mechanism whereby contracting muscle fibres are protected against cellular stress and injury.
authors.affiliation: Department of Medical Anatomy, The Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200, Copenhagen, Denmark. m.penkowa@mai.ku.dk
authors.forename: Milena
authors.initials: M
authors.lastname: Penkowa
authors.forename: Pernille
authors.initials: P
authors.lastname: Keller
authors.forename: Charlotte
authors.initials: C
authors.lastname: Keller
authors.forename: Juan
authors.initials: J
authors.lastname: Hidalgo
authors.forename: Mercedes
authors.initials: M
authors.lastname: Giralt
authors.forename: Bente Klarlund
authors.initials: BK
authors.lastname: Pedersen
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008668:Metallothionein / Q000096:biosynthesis*; D018485:Muscle Fibers, Skeletal / Q000378:metabolism / Q000502:physiology*; D009124:Muscle Proteins / Q000096:biosynthesis / Q000235:genetics; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology*; D018384:Oxidative Stress / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D009124:Muscle Proteins; D012333:RNA, Messenger; D008668:Metallothionein