title: Organ-specific control of glycolysis in anoxic turtles.
abstract: Control of glycolysis during anoxia was investigated in five organs (heart, brain, liver, and red and white skeletal muscles) of the freshwater turtle, Pseudemys scripta, after 1 or 5 h of submergence in N2-bubbled water. Lactate was produced as the metabolic end product, with distinct organ differences in the amount (net lactate accumulation was 2.4-fold higher in brain than white muscle) and rate (lactate production in liver dropped 16-fold after the 1st h) of lactate accumulation. ATP and total adenylate contents of all organs were reduced (by 15-32%) after 1 h of submergence, but energy charge was maintained; after 5 h, adenylate contents had fully recovered. Changes in the levels of hexose and triose phosphate intermediates of glycolysis indicated an activation of glycolysis within the 1st h of anoxia exposure in brain, heart, and skeletal muscles. By 5 h, however, these were reversed, and a glycolytic rate depression was indicated, consistent with the overall metabolic rate depression accompanying long-term anaerobiosis in the turtle. Crossover analysis indicated glycolytic control at the pyruvate kinase reaction in all organs during both glycolytic activation and metabolic depression; regulatory control at the phosphofructokinase locus was primarily important only during glycolytic activation in heart and red muscle. The same analysis indicated a very rapid glycolytic inhibition in liver occurring within the 1st h of anoxia exposure; this allows glycogenolysis to be directed toward glucose export yielding the fermentative fuel used by other organs during anoxia.
authors.affiliation: Department of Biology, Carleton University, Ottawa, Ontario, Canada.
authors.forename: D A
authors.initials: DA
authors.lastname: Kelly
authors.forename: K B
authors.initials: KB
authors.lastname: Storey
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000693:Anaerobiosis; D000818:Animals; D001921:Brain / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism; D006019:Glycolysis; D006600:Hexosephosphates / Q000378:metabolism; D007700:Kinetics; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D008099:Liver / Q000378:metabolism; D009132:Muscles / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D010100:Oxygen / Q000502:physiology*; D010732:Phosphofructokinase-1 / Q000378:metabolism; D011770:Pyruvate Kinase / Q000378:metabolism; D014426:Turtles / Q000378:metabolism*
chemical_list: D006600:Hexosephosphates; D007773:Lactates; D019344:Lactic Acid; D000255:Adenosine Triphosphate; D006003:Glycogen; D010732:Phosphofructokinase-1; D011770:Pyruvate Kinase; D010100:Oxygen