Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/64332
Type: Artigo de periódico
Title: EFFECT OF THAPSIGARGIN ON CALCIUM HOMEOSTASIS IN TRYPANOSOMA-CRUZI TRYPOMASTIGOTES AND EPIMASTIGOTES
Author: DOCAMPO, R
MORENO, SNJ
VERCESI, AE
Abstract: By using the fluorescent calcium indicator fura-2, it was found that the concentration of free Ca2+ in the cytoplasm of Trypanosoma cruzi trypomastigotes incubated in the presence or absence of external calcium was maintained at very low levels (10-20 nM). When trypomastigotes were incubated in the presence of succinate and ATP and permeabilized with digitonin, they lowered the medium calcium concentration to a submicromolar level. In the presence of 1 muM FCCP the initial rate of Ca2+ sequestration by these permeabilized cells was very slow. When succinate alone was present, the initial rate of Ca2+ accumulation was slower than with ATP plus succinate, and the calcium set point was about 0.6 muM. The succinate dependence and FCCP sensitivity of the later Ca2+ uptake indicate that it may be exerted by the mitochondria. High concentrations of the tumor promoter thapsigargin slightly increased cytosolic Ca2+ in the presence of extracellular Ca2+ but had no effect on the FCCP- and oligomycin/antimycin A-insensitive Ca2+ pool. In addition, when used at those concentrations (4-20 muM), thapsigargin was shown to release Ca2+ from the mitochondria and to decrease the inner mitochondrial membrane potential of trypomastigotes and epimastigotes as measured using safranine O. Despite the presence of inositol phosphates as determined by [H-3]inositol incorporation, no IP3-sensitive Ca2+ release could be detected in trypomastigotes.
Subject: CALCIUM
MITOCHONDRION
THAPSIGARGIN
TRYPANOSOMA-CRUZI
TRYPOMASTIGOTE
Country: Holanda
Editor: Elsevier Science Bv
Rights: fechado
Identifier DOI: 10.1016/0166-6851(93)90228-P
Date Issue: 1993
Appears in Collections:Unicamp - Artigos e Outros Documentos

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