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Type: Artigo de periódico
Title: Calcium mobilization by arachidonic acid in trypanosomatids
Author: Catisti, R
Uyemura, SA
Docampo, R
Vercesi, AE
Abstract: A recent report (Eintracht J, Maathai R, Mellors A, Ruben L. Calcium entry in Trypanosoma brucei is regulated by phospholipase A(2) and arachidonic acid, Biochem J 1998;336:659-66) provided evidence that calcium entry in Trypanosoma brucei bloodstream trypomastigotes is regulated via a signaling pathway involving phospholipase A(2)-mediated generation of arachidonic acid and stimulation of a plasma membrane-located calcium channel. Here we show that Ca2+ influx in T. brucei procyclic trypomastigotes, Leishmania donovani promastigotes and T. cruzi amastigotes was also stimulated in a dose-dependent manner (50-400 nM) by the amphiphilic peptide melittin. This effect was blocked by the phospholipase A(2) inhibitor 3-(4-octadecyl)-benzoylacrylic acid. The unsaturated fatty add arachidonic acid, in the range of 10-75 mu M, induced Ca2+ entry by a mechanism sensitive to LaCl3. However, both melittin and arachidonic acid induced an increase in [Ca2+](i) in T. brucei procyclic trypomastigotes incubated in Ca2+-free medium implying Ca2+ mobilization from intracellular stores. This hypothesis was supported by experiments showing that arachidonic acid promoted Ca2+ release from the acidocalcisomes of these cells. The results showing changes in mitochondrial membrane potential. release of acridine orange and Ca2+ from the acidocalcisomes and Ca2+ transport across the plasma membrane suggest that in addition to the possible stimulation of a Ca2+ channel-mediated process, arachidonic acid, in the range of concentrations used here: have other nonspecific effects on the trypanosomatids membranes. (C) 2000 Elsevier Science B.V. All rights reserved.
Subject: acidocalcisome
arachidonic acid
Country: Holanda
Editor: Elsevier Science Bv
Citation: Molecular And Biochemical Parasitology. Elsevier Science Bv, v. 105, n. 2, n. 261, n. 271, 2000.
Rights: fechado
Identifier DOI: 10.1016/S0166-6851(99)00186-3
Date Issue: 2000
Appears in Collections:Unicamp - Artigos e Outros Documentos

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