Erowid References Database
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Hariri M.
“Uptake of 5-Hydroxytryptamine by Mesocestoides Corti (Cestoda).”.
J Parasitol. 1975;61(3):440-448.
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Abstract
The kinetics of the uptake of 5-hydroxytryptamine (5HT) in tetrathyridia of Mesocestoides corti were studied. Methods Tetrathyridia of M.corti were maintained in mice. Animals were killed and tetrathyridia removed froni the body cavity. They were incubated with 14C-5HT (Sigma-Chem.) for up to 48 hr after which they were homogenized, centrifuged and an extract of the aupernatant assayed for 5HT fluorometrically after ninhydrin reaction. Incubation of the organism with 10 4 M of tryptophan (Sigma-Chem.) pargyline (Abbott), iproniazid and nialamide (both from Sigma-Chem) (all at 1 x 10 3 M), alpha - propyldopacetamide (Aldrich) and 6-fluorotryptophan (Regis) (both 1 x 10 4 M) did not alter 5HT level. 5-Hydroxytryptophan (Sigma-Chem.) increased 5HT level. The uptake of 5HT at 37° C was initially rapid (2 ng/mg protein from 10 6 M 5HT at 10 min) and did not reach a constant level at 60 min. 2 Saturable systems-were involved: a high affinity system with a Michaelis constant (Km) of 1.4 x 10 M and Vmax of 0.54 ngmg protein/2 min. and a low affinity system with Km of 2.5 x 10 6 M and Vmax 2.56 ng/mg protein/2 min. 5HT Uptake was inhibited by chlorimipramine (CIBA-Geigy), protriptyline, p - chloramphetamine, p - chlorometamphetamine (both Regis) and ouabain (Sigma-Chem,) (10 -5 M). LSD and 2-bromo-LSD were much less potent inhibitors. Methysergide (Sandoz) and 1-methyl-LSD had almoat no inhibitory effect on 5HT uptake' while 2 other 5HT blocking agent 8-beta-carbobenzyloxyaminomethyl-1,6 dimethyl - l0-alpha- ergotine (Farmitalia) and cyproheptadine (Merck-USA) had equally Strong inhibitory effects. The worms were able to retain most of their 5HT for 180 min. Uptake of 14C-noradrenaline (NE) (Sigma - Chem.) was less than that of 14C-5HT. The uptake procea9 wa9 9tereoBpecific having a greater affinity for (-)-NE than for (+) - NE. 5HT Uptake was reduced at low temperature. Conclusion The high affinity 5HT uptake mechanism of M.corti provides a means of supplying the organism with thia neurotransmitter which it may not be able to Synthesize.
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