Received October 18, 2004
Revised November 22, 2004
Accepted after revision December 20, 2004
Human/environmental and exercise physiology
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EXERCISE-INDUCED METALLOTHIONEIN EXPRESSION IN HUMAN
SKELETAL MUSCLE FIBRES
Milena Penkowa 1*,
Pernille Keller 2,
Charlotte Keller 2,
Juan Hidalgo 3,
Mercedes Giralt 3,
Bente Klarlund Pedersen 2
1 The Panum Institute
2 Rigshospitalet
3 Institute of Neurosciences
* To whom correspondence should be addressed. E-mail: m.penkowa{at}mai.ku.dk.
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Abstract |
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Exercise induces free oxygen radicals that cause oxidative stress, and metallothioneins (MT) 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 relation to 3 hours 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, at 24 hours post-exercise the levels of MT-II mRNA and MT-I+II proteins were still highly increased and the MT-II mRNA expression was reaching a 15-fold increase.
As expected, immunohistochemistry 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 t 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 likely represent a mechanism whereby contracting muscle fibres are protected against cellular stress and injury.
Key Words:
Antioxidant, Free radical, Human
