title: Praziquantel has no direct effect on (Na(+)+K+)-ATPases and (Ca2(+)-Mg2+)ATPases of Schistosoma mansoni.
abstract: Therapeutic concentrations of praziquantel produce a rapid and intense contraction of the human flatworm Schistosoma mansoni. As an action on ATPases responsible for calcium homeostasis arises as a possible explanation for the molecular mechanism of this effect, we tested here the effect of praziquantel on different preparations from male adult worms that were previously characterized for their content in (Na(+)+K+)-ATPase and (Ca2(+)-Mg2+)ATPase activities from different origins. Concentrations as high as 100 microM praziquantel did not inhibit (Na(+)+K+)-ATPase from tegument and carcass nor (Ca2(+)-Mg2+)ATPase from heterogeneous (P1) and microsomal (P4) fractions. As 100 microM praziquantel was also without effect on calcium permeability of microsomal vesicles actively loaded with 45Ca2+, the present results discard three hypotheses recently raised for the mechanism of praziquantel-induced contraction of S. mansoni.
authors.affiliation: Departamento de Farmacologia Básica e Clínica, Instituto de CiênciasBiomédicas, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: V M
authors.initials: VM
authors.lastname: Cunha
authors.forename: F
authors.initials: F
authors.lastname: Noël
mesh_terms: D000818:Animals; D000980:Antiplatyhelmintic Agents / Q000494:pharmacology*; D017301:Ca(2+) Mg(2+)-ATPase / Q000037:antagonists & inhibitors / Q000187:drug effects*; D002118:Calcium / Q000493:pharmacokinetics; D002132:Calcium Radioisotopes; D002463:Cell Membrane Permeability / Q000187:drug effects; D015801:Helminth Proteins / Q000037:antagonists & inhibitors / Q000187:drug effects*; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000187:drug effects*; D008297:Male; D051379:Mice; D008861:Microsomes / Q000187:drug effects / Q000378:metabolism; D011223:Praziquantel / Q000494:pharmacology*; D012550:Schistosoma mansoni / Q000187:drug effects* / Q000201:enzymology*; D012908:Snails / Q000469:parasitology; D000254:Sodium-Potassium-Exchanging ATPase / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000980:Antiplatyhelmintic Agents; D002132:Calcium Radioisotopes; D015801:Helminth Proteins; D007527:Isoenzymes; D011223:Praziquantel; D017301:Ca(2+) Mg(2+)-ATPase; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium