title: Strong alkalinization in the anterior midgut of larval yellow fever mosquitoes (Aedes aegypti): involvement of luminal Na+/K+-ATPase.
abstract: Recently, Na(+)/K(+)-ATPase has been detected in the luminal membrane of the anterior midgut of larval yellow fever mosquitoes (Aedes aegypti) with immunohistochemical techniques. In this study, the possible involvement of this ATPase in strong alkalinization was investigated on the level of whole larvae, isolated and perfused midgut preparations and on the molecular level of the Na(+)/K(+)-ATPase protein. Ouabain (5 mM) did not inhibit the capability of intact larval mosquitoes to alkalinize their anterior midgut. Also in isolated and perfused midgut preparations the perfusion of the lumen with ouabain (5 mM) did not result in a significant change of the transepithelial voltage or the capacity of luminal alkalinization. Na(+)/K(+)-ATPase activity was completely abolished when KCl was substituted with choline chloride, suggesting that the enzyme cannot act as an ATP-driven Na(+)/H(+)-exchanger. Altogether the results of the present investigation indicate that apical Na(+)/K(+)-ATPase is not of direct importance for strong luminal alkalinization in the anterior midgut of larval yellow fever mosquitoes.
authors.affiliation: Department of Biological Sciences, Wagner College, Staten Island, New York 10301, USA. horst.onken@wagner.edu
authors.forename: Horst
authors.initials: H
authors.lastname: Onken
authors.forename: Malay
authors.initials: M
authors.lastname: Patel
authors.forename: Margarita
authors.initials: M
authors.lastname: Javoroncov
authors.forename: Sejmir
authors.initials: S
authors.lastname: Izeirovski
authors.forename: Stacia B
authors.initials: SB
authors.lastname: Moffett
authors.forename: David F
authors.initials: DF
authors.lastname: Moffett
mesh_terms: D000330:Aedes / Q000201:enzymology*; D000818:Animals; D002794:Choline / Q000494:pharmacology; D055664:Electrochemical Techniques; D004791:Enzyme Inhibitors / Q000494:pharmacology; D041981:Gastrointestinal Tract / Q000187:drug effects / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007814:Larva; D010042:Ouabain / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase; D002794:Choline