Estresse oxidativo em camundongos knockout para o receptor de LDL : papel dos substratos redutores de NADP+ mitocondrial e dos niveis de Ca POT.2+ intracelular / Oxidative stress in LDL receptor knockout mice : role of NADP+ linked substrates and intracellular Ca POT.2+ levels

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

In this work, oxidative stress in liver mitochondria isolated from LDLr-/- mice was further characterized by showing a lower mitochondrial isocitrate content, lower matochondrial GSH/GSSG ratio and a higher liver content of protein carbonyls as compared to control mice. The higher rate of ROS production in LDLr -/- mitochondria was also prevented by the presence of exogenous isocitrate which maintains NADP+ fully reduced. Similar results were obtained when the annimals were treated with drinking water containing 55 mM sodium citrate/67 mM citric acid during two weeks, when was observed lower levels of ROS production, an improve in the rate of oxygen consumption supported by NADP-linked substrates as well as a higher capacity to sustain reduced NAD(P)H in liver mitochondria. The spleen lymphocytes isolated from k/o mice also showed higher ROS generation by lymphocyte mitochondria and whole cell, and higher levels of cytosolic and mitochondrial Ca2+ compared to control mice. As intracellular Ca2+ has been shown to affect Th1 and Th2 priming and lymphocyte activation we evaluated some cytokines in LDL receptor k/o mice compared to controls. Th1 cytokines (interleukin-2 and TNF-?), as well as Th2 cytokines (interleukin-10 and interleukin-4) were higher in k/o mice than in control. The increase of Th1 and Th2 cytokines, ROS generation, and Ca2+ concentration were partially inhibited by treatment of the k/o mice with verapamil, an L-type Ca2+ channel antagonist. In conclusion, the data demonstrate that the liver mitochondrial oxidative stress in hypercholesterolemic LDL receptor knockout mice is the result of a low content of mitochondrial NADPH-linked substrates in the intact animal that can be, at least in part, replenished by oral administration of citrate. Also, we demonstrate that Ca2+ presents a central role in spleen mononuclear cell from hypercholesterolemic LDL receptor knockout mice modulating ROS generation and cytokines production. These alterations are probably related to lymphocyte activation due the expontaneous atherosclerotic lesion observed in aortic arch of k/o mice

ASSUNTO(S)

hypercholesterolemia mitocondria hipercolesterolemia mitochondria citocinas cytokines

ACESSO AO ARTIGO

Documentos Relacionados