Characteristics of Ca2+ transport by Trypanosoma cruzi mitochondria in situ

Arch Biochem Biophys. 1989 Jul;272(1):122-9. doi: 10.1016/0003-9861(89)90202-6.

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 (beta-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 microM. 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 beta-lapachone. However, when ascorbate plus N,N,N',N'-tetramethyl-p-phenylenediamine in the presence of antimycin A was used as subtrate, beta-lapachone caused pyridine nucleotide oxidation, and Ca2+ accumulation by these mitochondria was considerably lower than in control preparations, this effect being dose-dependent.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Diphosphate / pharmacology
  • Animals
  • Biological Transport
  • Calcium / metabolism*
  • Calcium / pharmacology
  • Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / pharmacology
  • Cell Membrane Permeability / drug effects
  • Digitonin / pharmacology
  • Egtazic Acid / pharmacology
  • Intracellular Membranes / metabolism
  • Male
  • Membrane Potentials / drug effects
  • Mitochondria / drug effects
  • Mitochondria / metabolism*
  • Mitochondria, Liver / drug effects
  • Mitochondria, Liver / metabolism
  • NADP / metabolism
  • Naphthoquinones / pharmacology
  • Onium Compounds
  • Organophosphorus Compounds
  • Oxidation-Reduction
  • Peroxides / pharmacology
  • Phosphorylation
  • Rats
  • Rats, Inbred Strains
  • Trypanosoma cruzi / ultrastructure*
  • tert-Butylhydroperoxide

Substances

  • Naphthoquinones
  • Onium Compounds
  • Organophosphorus Compounds
  • Peroxides
  • Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone
  • beta-lapachone
  • Egtazic Acid
  • NADP
  • Adenosine Diphosphate
  • tert-Butylhydroperoxide
  • Digitonin
  • Calcium
  • tetraphenylphosphonium