Open AccessVoltage‐dependent potassium currents expressed in X enopus laevis oocytes after injection of m RNA isolated from trophozoites of G iardia lamblia (strain P ortland‐1)
Author(s) -
Ponce Arturo,
JimenezCardoso Enedina,
EligioGarcia Leticia
Publication year - 2013
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.1002/phy2.186
Subject(s) - xenopus , quinidine , potassium channel , messenger rna , giardia lamblia , ion channel , membrane potential , biology , potassium channel blocker , biophysics , chemistry , microbiology and biotechnology , biochemistry , pharmacology , gene , receptor
Despite its importance as a health problem issue, almost nothing is known about the membrane physiology of G iardia lamblia and practically there exist no information so far regarding the variety and properties of ion channels that this protozoan parasite possesses. To address this subject we resorted to an indirect method, consisting in the injection of m RNA and further characterization of ion currents in X enopus oocytes. In this work, we show that oocytes injected with m RNA isolated from cultured trophozoites of G . lamblia , strain Portland‐1 express novel potassium currents that appear over the second day after injection and show time‐ and voltage‐dependent activation followed by a slow inactivation. They start activating at −90 mV, with V 1/2 of −30 mV; its time constant of activation (at +60 mV) is 0.11 sec, whereas that of inactivation is 1.92 sec, V 1/2 = −44.6 mV. Such K currents were effectively blocked by K channel blockers TEA and 4AP, as well as Ba 2+ , quinine, quinidine, charybdotoxin, dendrotoxin‐1, capsaicin, margatoxin, and diltiazem. These results suggest that such currents are the result of expression of Giardia′s voltage‐gated K channels heterologously expressed in X enopus laevis oocytes.