Characterization of glucose uptake by Trichuris globulosa (Nematoda) in vitro.
14C-glucose uptake by adult Trichuris globulosa is found to be a non-linear function of time and limiting substrate concentration. The uptake is a two component process, an initial rapid burst is followed by a lower steady state, implying a mediated process. The uptake is dependent on Na+ ions which cannot be replaced by K+, Li+ or choline. The uptake is also dependent on pH, being maximal at pH 7.4. 14C-glucose absorption is markedly inhibited by glucose, phlorizin, ouabain and to a smaller extent by a number of monosaccharides and other sugar-phosphates, nucleosides and metabolic inhibitors like p-nitrophenyl phosphate and iodoacetate. The inhibition constant for glucose, phlorizin and ouabain has been found to be 8 mM, 5 mM and 7 mM, respectively. A modified Dixon-plot shows that glucose is a completely competitive inhibitor for 14C-glucose uptake while the nature of competitive inhibition of phlorizin and ouabain are found to be partial.
Jasra
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N
Department of Zoology, Panjab University, Chandigarh, India.
Sanyal
S N
SN
Khera
S
S
D000042:Absorption; D000249:Adenosine Monophosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001667:Binding, Competitive; D005947:Glucose / Q000378:metabolism* / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007461:Iodoacetates / Q000494:pharmacology; D019807:Iodoacetic Acid; D007700:Kinetics; D008320:Maltose / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D010695:Phlorhizin / Q000494:pharmacology; D014258:Trichuris / Q000378:metabolism*
D007461:Iodoacetates; D000249:Adenosine Monophosphate; D010042:Ouabain; D008320:Maltose; D000255:Adenosine Triphosphate; D010695:Phlorhizin; D005947:Glucose; D019807:Iodoacetic Acid