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Effects of Extracellular Potassium on Acid Release and Motility Initiation in Toxoplasma gondii
Author(s) -
ENDO TAKURO,
TOKUDA HAJIME,
YAGITA KENJI,
KOYAMA TSUTOMU
Publication year - 1987
Publication title -
the journal of protozoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 0022-3921
DOI - 10.1111/j.1550-7408.1987.tb03177.x
Subject(s) - nigericin , motility , extracellular , potassium , chemistry , biophysics , toxoplasma gondii , suspension (topology) , sodium , biochemistry , membrane , biology , microbiology and biotechnology , antibody , immunology , mathematics , organic chemistry , homotopy , pure mathematics
The internal pH (pH i ) of Toxoplasma gondii was estimated by measuring the accumulation of the weak base 9‐aminoacridine in buffers with various ionic compositions. The pH i of the metabolizing parasite increased when the extracellular K + was elevated in alkaline medium or when the external pH (pH c ) was substantially increased in medium employing high external K + (90 mM). The parasite in mouse peritoneal fluid, or in potassium sulfate buffer (pH 8.2), where the pH i was demonstrated to be increased to 7.9, became motile when acidic buffer was substituted for the original suspension medium. This acid‐induced independent movement subsided within 5 min but was repeatedly induced if the pH c was serially lowered to 6.0. Basic buffers, on the other hand, abolished motility when applied to the moving parasites. Nigericin, which is known to collapse pH gradients across the membrane, also abolished motility.