title: Local hindlimb antioxidant infusion does not affect muscle glucose uptake during in situ contractions in rat.
abstract: There is evidence that reactive oxygen species (ROS) contribute to the regulation of skeletal muscle glucose uptake during highly fatiguing ex vivo contraction conditions via AMP-activated protein kinase (AMPK). In this study we investigated the role of ROS in the regulation of glucose uptake and AMPK signaling during low-moderate intensity in situ hindlimb muscle contractions in rats, which is a more physiological protocol and preparation. Male hooded Wistar rats were anesthetized, and then N-acetylcysteine (NAC) was infused into the epigastric artery (125 mg.kg(-1).h(-1)) of one hindlimb (contracted leg) for 15 min before this leg was electrically stimulated (0.1-ms impulse at 2 Hz and 35 V) to contract at a low-moderate intensity for 15 min. The contralateral leg did not receive stimulation or local NAC infusion (rest leg). NAC infusion increased (P<0.05) plasma cysteine and cystine (by approximately 360- and 1.4-fold, respectively) and muscle cysteine (by 1.5-fold, P=0.001). Although contraction did not significantly alter muscle tyrosine nitration, reduced (GSH) or oxidized glutathione (GSSG) content, S-glutathionylation of protein bands at approximately 250 and 150 kDa was increased (P<0.05) approximately 1.7-fold by contraction, and this increase was prevented by NAC. Contraction increased (P<0.05) skeletal muscle glucose uptake 20-fold, AMPK phosphorylation 6-fold, ACCbeta phosphorylation 10-fold, and p38 MAPK phosphorylation 60-fold, and the muscle fatigued by approximately 30% during contraction and NAC infusion had no significant effect on any of these responses. This was despite NAC preventing increases in S-glutathionylation with contraction. In conclusion, unlike during highly fatiguing ex vivo contractions, local NAC infusion during in situ low-moderate intensity hindlimb contractions in rats, a more physiological preparation, does not attenuate increases in skeletal muscle glucose uptake or AMPK signaling.
authors.affiliation: Department of Physiology, The University of Melbourne, Parkville, Victoria 3010, Australia. t.merry@pgrad.unimelb.edu.au
authors.forename: T L
authors.initials: TL
authors.lastname: Merry
authors.forename: R M
authors.initials: RM
authors.lastname: Dywer
authors.forename: E A
authors.initials: EA
authors.lastname: Bradley
authors.forename: S
authors.initials: S
authors.lastname: Rattigan
authors.forename: G K
authors.initials: GK
authors.lastname: McConell
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000111:Acetylcysteine / Q000008:administration & dosage* / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage* / Q000378:metabolism; D001692:Biological Transport; D001794:Blood Pressure; D003545:Cysteine / Q000097:blood; D003553:Cystine / Q000097:blood; D004558:Electric Stimulation; D005947:Glucose / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism; D006339:Heart Rate; D006614:Hindlimb; D007261:Infusions, Intra-Arterial; D008297:Male; D009119:Muscle Contraction; D018763:Muscle Fatigue; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000098:blood supply / Q000187:drug effects* / Q000294:innervation / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D012039:Regional Blood Flow; D013997:Time Factors; D014443:Tyrosine / Q000378:metabolism; D014655:Vascular Resistance; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D014443:Tyrosine; D003553:Cystine; D048051:p38 Mitogen-Activated Protein Kinases; D055372:AMP-Activated Protein Kinases; D005978:Glutathione; D005947:Glucose; D003545:Cysteine; D000111:Acetylcysteine