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|Type:||Artigo de periódico|
|Title:||Characteristics Of Ca2+ Transport By Trypanosoma Cruzi Mitochondria In Situ|
|Abstract:||The use of digitonin to permeabilize Trypanosoma cruzi plasma membrane has allowed the study of Ca2+ transport and oxidative phosphorylation in mitochondria in situ (R. Docampo and A. E. Vercesi (1989) J. Biol. Chem. 264, 108-111). The present results show that these mitochondria are able to build up and retain a membrane potential as indicated by a tetraphenylphosphonium-sensitive electrode. Ca2+ uptake caused membrane depolarization compatible with the existence of an electrogenically mediated Ca2+ transport mechanism in these mitochondria. Addition of Ca2+ or ethylene glycol bis (β-aminoethyl ether) N-N′-tetraacetic acid to these preparations under steady-state conditions was followed by Ca2+ uptake or release, respectively, tending to restore the original Ca2+ "set point" at about 0.9 μm. In addition, large amounts of Ca2+ were retained by T. cruzi mitochondria even after addition of thiols and NAD(P)H oxidants such as t-butyl hydroperoxide, diamide, and the 1,2-naphthoquinone β-lapachone. However, when ascorbate plus N,N,N′,N′-tetramethyl-p-phenylenediamine in the presence of antimycin A was used as subtrate, β-lapachone caused pyridine nucleotide oxidation, and Ca2+ accumulation by these mitochondria was considerably lower than in control preparations, this effect being dose-dependent. © 1989.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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