5-hydroxytryptamine, glucose uptake, glycogen utilization and carbon dioxide fixation in Hymenolepis microstoma (Cestoda).
1. In vitro glucose uptake and glycogen utilization by Hymenolepis microstoma decreased under high oxygen concentrations. 2. 5-Hydroxytryptamine did not stimulate in vitro glucose uptake but did increase glycogen utilizations by H. microstoma. 3. The reduced glucose uptake under high oxygen concentrations (21 and 95%) resulted in a reduction in excretory products. 4. 14CO2-incorporation studies confirmed that, under both 95% O2:5% CO2 and air-minus-CO2 (identical to 21% O2). CO2-fixation by phosphoenolpyruvate carboxykinase (EC 4.1.1.32) was inhibited. 5. The specific activity of hexokinase (EC 2.7.1.1), phosphofructokinase (EC 2.7.1.11) and pyruvate kinase (EC 2.7.1.40) was not stimulated by 5-HT. 6. The concentration of ATP required for optimal stimulation of phosphofructokinase activity was 0.67 mM. Activity was further significantly increased by the addition of cAMP and even greater by AMP.
D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D006003:Glycogen / Q000378:metabolism*; D006019:Glycolysis; D006926:Hymenolepis / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D012701:Serotonin / Q000494:pharmacology*
D002245:Carbon Dioxide; D012701:Serotonin; D006003:Glycogen; D005947:Glucose