Ca2+ transport by coupled Trypanosoma cruzi mitochondria in situ.
The use of digitonin to permeabilize Trypanosoma cruzi plasma membrane enabled us to study Ca2+ transport and oxidative phosphorylation in mitochondria in situ. Addition of Ca2+ to these preparations evoked a cycle of respiratory stimulation. Ca2+ uptake was partially inhibited by ruthenium red, almost totally inhibited by antimycin A, and stimulated by inorganic phosphate. Addition of carbonyl cyanide p-trifluoromethoxyphenylhydrazone to digitonin-permeabilized T. cruzi epimastigotes under steady-state conditions was followed by Ca2+ release. Antimycin A- and carbonyl cyanide p-trifluoromethoxyphenylhydrazonein-sensitive Ca2+ uptake was also detected in digitonin-permeabilized epimastigotes. Accordingly, ATP stimulated Ca2+ uptake by preparations de-energized by oligomycin and antimycin A. In conclusion, in contrast to previous reports indicating that a Ca2+ transport system occurs only in mitochondria from vertebrate tissues, T. cruzi epimastigotes also possess a similar system. In addition, these protozoan mitochondria have an extremely high resistance to the deleterious effects of massive Ca2+ loads in comparison with most types of mammalian mitochondria.
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Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Cidade Universitária, Brazil.
Vercesi
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D000818:Animals; D000968:Antimycin A / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D004072:Digitonin; D007700:Kinetics; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009840:Oligomycins / Q000494:pharmacology; D010101:Oxygen Consumption / Q000187:drug effects; D010539:Permeability; D014349:Trypanosoma cruzi / Q000378:metabolism*
D009840:Oligomycins; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D000001:Calcimycin; D000968:Antimycin A; D004072:Digitonin; D002118:Calcium