AMP-activated protein kinase kinase activity and phosphorylation of AMP-activated protein kinase in contracting muscle of sedentary and endurance-trained rats

• Published in: American journal of physiology: endocrinology and metabolism 2005-10, Vol.289 (4), p.E710-E715
• Main Authors: Hurst, Denise, Taylor, Eric B, Cline, Troy D, Greenwood, Lyle J, Compton, Cori L, Lamb, Jeremy D, Winder, William W
• Format: Article
• Language: English
• Subjects: Animals; Electric Stimulation; Enzyme Activation; Isometric Contraction - physiology; Male; Muscle, Skeletal - innervation; Muscle, Skeletal - physiology; Phosphorylation; Physical Conditioning, Animal - methods; Physical Endurance - physiology; Protein Kinases - metabolism; Rats; Rats, Sprague-Dawley; Rest - physiology
• ISSN: 0193-1849; 1522-1555
• DOI: 10.1152/ajpendo.00155.2005

Department of Physiology and Developmental Biology, Brigham Young University, Provo, Utah Submitted 7 April 2005 ; accepted in final form 17 May 2005 This study was designed to examine activity of AMP-activated protein kinase kinase (AMPKK) in muscles from nontrained and endurance-trained rats. Rats were trained 5 days/wk, 2 h/day for 8 wk at a final intensity of 32 m/min up a 15% grade with 30-s sprints at 53 m/min every 10 min. Gastrocnemius muscles were stimulated in situ in trained and nontrained rats for 5 min at frequencies of 0.4/s and 1/s. Gastrocnemius LKB1 protein, a putative component of the AMPKK complex (LKB1, STRAD, and MO25), increased approximately twofold in response to training. Phosphorylation of AMP-activated protein kinase (AMPK) determined by Western blot and AMPK activity of immunoprecipitates (both isoforms) was increased at both stimulation rates in both trained and nontrained muscles. AMPKK activity was 73% lower in resuspended polyethylene glycol precipitates of muscle extracts from the trained compared with nontrained rats. AMPKK activity did not increase in either trained or nontrained muscle in response to electrical stimulation, even though phospho-AMPK did increase. These results suggest that AMPKK is activated during electrical stimulation of both trained and nontrained muscle by mechanisms other than covalent modification. AMP-activated protein kinase; adenosine 5'-triphosphate; metabolism; skeletal muscle; serine/threonine kinase 11 Address for reprint requests and other correspondence: W. W. Winder, 545 WIDB, Brigham Young University, Provo, UT 84602 (email: william_winder{at}byu.edu )