title: Leishmania amazonensis: characterization of an ouabain-insensitive Na+-ATPase activity.
abstract: We characterized ouabain-insensitive Na+-ATPase activity present in the plasma membrane of Leishmania amazonensis and investigated its possible role in the growth of the parasite. An increase in Na+ concentration in the presence of 1mM ouabain, increased the ATPase activity with a V(max) of 154.1+/-13.5nmol Pi x h(-1) x mg(-1) and a K0.5 of 28.9+/-7.7mM. Furosemide and sodium orthovanadate inhibited the Na+-stimulated ATPase activity with an IC(50) of 270microM and 0.10microM, respectively. Furosemide inhibited the growth of L. amazonensis after 48h incubation, with maximal effect after 96h. The IC50 for furosemide was 840. On the other hand, ouabain (1mM) did not change the growth of the parasite. Taken together, these results show that L. amazonensis expresses a P-type, ouabain-insensitive Na+-ATPase that could be involved with the growth of the parasite.
authors.affiliation: Laboratório de Bioquímica Celular, Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, CCS, Bloco H sala H2-013, Cidade Universitária, Ilha do Fundão, 21941-590, Rio de Janeiro, RJ, Brazil.
authors.forename: Elmo Eduardo
authors.initials: EE
authors.lastname: de Almeida-Amaral
authors.forename: Celso
authors.initials: C
authors.lastname: Caruso-Neves
authors.forename: Vanessa Maria Pereira
authors.initials: VM
authors.lastname: Pires
authors.forename: José Roberto
authors.initials: JR
authors.lastname: Meyer-Fernandes
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D027682:Cation Transport Proteins / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005665:Furosemide / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007894:Leishmania mexicana / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development*; D016774:Leishmaniasis, Diffuse Cutaneous / Q000469:parasitology; D010042:Ouabain / Q000494:pharmacology*; D012964:Sodium / Q000378:metabolism; D049994:Sodium Potassium Chloride Symporter Inhibitors / Q000494:pharmacology; D014638:Vanadates / Q000494:pharmacology