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Regulation of the intracellular pH in the protozoan parasite Trypanosoma brucei brucei.
Journal article

Regulation of the intracellular pH in the protozoan parasite Trypanosoma brucei brucei.

  • 1997-11-05
Published in:
  • Biological chemistry. - 1997
4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid
Amiloride
Animals
Bicarbonates
Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone
Cytosol
Diuretics
Enzyme Inhibitors
Ethylmaleimide
Fluoresceins
Fluorescent Dyes
Hydrogen-Ion Concentration
Nigericin
Proton-Translocating ATPases
Pyruvic Acid
Sodium-Hydrogen Exchangers
Trypanosoma brucei brucei
English The mechanisms regulating the intracellular pH (pHi) in both forms of Trypanosoma brucei brucei (cultured cells) were investigated using the fluorescent probe 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF). The pHi values measured were 7.22+/-0.03 in the procyclics and 7.40+/-0.05 in the bloodstream form. In the presence of 24mM HCO3-, pHi values were slightly higher in both forms of trypanosomes suggesting a bicarbonate-linked pH regulation. pHi was more stable in procyclics (between 7.15 and 7.30 in the external pH range 6.4-7.6) than in the bloodstream forms. The amiloride analogue tested decreased pHi, suggesting Na+-driven Na+/H+ antiporters. H+-ATPases also seem to be involved in pHi regulation since the inhibitors N-ethylmaleimide (1 mM) and N,N'-dicyclohexylcarbodiimide (80 microM) induced a rapid acidification in both forms of trypanosomes. Addition of pyruvate caused a cytosol acidification in the bloodstream form only confirming the existence of a diffusion-facilitated carrier for pyruvate, with the cotransport of H+. Our results show that, although similar pH regulation mechanisms seem to exist in both forms of trypanosomes, the procyclics can regulate efficiently their pHi and consequently their plasma membrane potential whereas the bloodstream forms cannot always maintain their pHi and are easily depolarized following a small acid load.
Language
  • English
Open access status
closed
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Persistent URL
https://sonar.ch/global/documents/145456
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