title: AMP-activated protein kinase plays a role in initiating metabolic rate suppression in goldfish hepatocytes.
abstract: In the present study, we test the hypothesis that AMP-activated protein kinase (AMPK) initiates metabolic rate suppression in isolated goldfish hepatocytes. To accomplish this, we attempted to pharmacologically activate AMPK in goldfish hepatocytes with 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) and the thienopyridone, A769662, to examine the effects of AMPK activation on eukaryotic elongation factor-2 (eEF2), protein synthesis, and cellular oxygen consumption rate ([Formula: see text]). Goldfish hepatocytes treated with 1 mM AICAR under normoxic conditions (>200 μM O(2)) showed a modest but significant 1.1-fold increase in AMPK phosphorylation, a 7.5-fold increase in AMPK activity, a 1.4-fold increase in eEF2 phosphorylation, and a 24% decrease in [Formula: see text]. At physiologically relevant [O(2)] (<40 μM O(2)), the addition of 1 mM AICAR resulted in only a 13% decrease in cellular [Formula: see text] with no change in sensitivity to [O(2)] as assessed by estimates of cellular P(50) and P(90) values. The addition of compound C, a general protein kinase inhibitor, after AICAR incubation did not reverse the effects of AICAR on [Formula: see text] in normoxia. Treatment of hepatocytes with ≤200 μM A769662 did not affect AMPK activity, AMPK phosphorylation, eEF2 phosphorylation, or cellular [Formula: see text]. These data suggest that A769662 is not an activator of AMPK in goldfish hepatocytes. Although our study provides support for the hypothesis that AMPK plays a role in initiating metabolic rate suppression in goldfish hepatocytes, this support must be viewed cautiously because of the known off-target effects of the pharmacological agents used.
authors.affiliation: Department of Zoology, The University of British Columbia, 6270 University Blvd, Vancouver, BC, V6T 1Z4, Canada. glau@zoology.ubc.ca
authors.forename: Gigi Y
authors.initials: GY
authors.lastname: Lau
authors.forename: Jeffrey G
authors.initials: JG
authors.lastname: Richards
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000818:Animals; D015687:Cell Hypoxia / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D006054:Goldfish / Q000378:metabolism*; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D014176:Protein Biosynthesis / Q000187:drug effects; D012263:Ribonucleosides / Q000494:pharmacology*; D058924:Thienopyridines / Q000494:pharmacology*
chemical_list: D015852:Eukaryotic Initiation Factor-2; D012263:Ribonucleosides; D058924:Thienopyridines; D055372:AMP-Activated Protein Kinases