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Isoform‐specific and exercise intensity‐dependent activation of 5′‐AMP‐activated protein kinase in human skeletal muscle
Author(s) -
Wojtaszewski Jørgen F. P.,
Nielsen Pernille,
Hansen Bo F.,
Richter Erik A.,
Kiens Bente
Publication year - 2000
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2000.t01-1-00221.x
Subject(s) - ampk , amp activated protein kinase , skeletal muscle , protein kinase a , endocrinology , medicine , chemistry , phosphorylation , biochemistry
1 5′‐AMP‐activated protein kinase (AMPK) has been suggested to play a key role in the regulation of metabolism in skeletal muscle. AMPK is activated in treadmill‐exercised and electrically stimulated rodent muscles. Whether AMPK is activated during exercise in humans is unknown. 2 We investigated the degree of activation and deactivation of α‐isoforms of AMPK during and after exercise. Healthy human subjects performed bicycle exercise on two separate occasions at either a low (∼50% maximum rate of O 2 uptake (V̇ O2,max ) for 90 min) or a high (∼75% V̇ O2,max for 60 min) intensity. Biopsies from the vastus lateralis muscle were obtained before and immediately after exercise, and after 3 h of recovery. 3 We observed a 3‐ to 4‐fold activation of the α2‐AMPK isoform immediately after high intensity exercise, whereas no activation was observed after low intensity exercise. The activation of α2‐AMPK was totally reversed 3 h after exercise. In contrast, α1‐AMPK was not activated during either of the two exercise trials. 4 The in vitro AMP dependency of α2‐AMPK was significantly greater than that of α1‐AMPK (∼3‐ vs. ∼2‐fold). 5 We conclude that in humans activation of α2‐AMPK during exercise is dependent upon exercise intensity. The stable activation of α2‐AMPK, presumably due to the activation of an upstream AMPK kinase, is compatible with a role for this kinase complex in the regulation of skeletal muscle metabolism during exercise, whereas the lack of stable α1‐AMPK activation makes this kinase complex a less likely candidate.