MiP2005: Session 9

Mitochondrial Physiology Network 10.9: 105-106 (2005) - download pdf

 

Hypertriglyceridemia in transgenic mice is associated with higher mitochondrial resting respiration and increased whole body CO2 production and body temperature.

Helena CF Oliveira, LC Alberici, KG Zecchin, AE Vercesi

Depto. Patologia Clínica, Faculdade de Ciências Médicas; Depto. Fisiologia e Biofísica, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil. - ho98@unicamp.br

    High plasma levels of triglycerides lead to an increase in liver mitochondria resting respiration rate and predispose to mitochondrial permeability transition (MPT) [1]. In the present study, we demonstrate that spleen lymphocytes isolated from hypertriglyceridemic transgenic mice also present resting oxygen consumption rates 54 % higher when compared to spleen lymphocytes isolated from control mice. No significant alterations in the transmembrane mitochondrial potential or reactive oxygen species production could be detected through DHE or H2DCF-DA fluorescence method. Fibrate treatment reduced triglyceride plasma levels by 50 % and normalized liver mitochondrial resting respiration. However, insulin treatment, which reduced triglyceride plasma levels by 30 %, did not correct the liver mitochondrial respiratory control in transgenic mice. When submitted to oxidative stress, liver mitochondria isolated from transgenic mice showed higher susceptibility to lipid peroxidation induced by Fe(II)/citrate than control liver mitochondria. In agreement with the results of mitochondria resting respiration (isolated and in situ), whole mice CO2 production rate was higher in the hypertriglyceridemic transgenic than in control mice (14.8 ± 1.1 vs. 12.6 ± 1.5 g∙kg-1∙h-1, P<0.05, respectively). In addition, body temperature was also higher in transgenic than in control mice (37 ± 0.4 °C vs. 36.3 ± 0.2 °C, P<0.05, respectively). We propose that this faster catabolism may represent a regulated adaptation to oxidize excess free fatty acids in these hypertriglyceridemic transgenic mice.

     Supported by FAPESP, CNPq.

1.  Alberici LC, Oliveira HCF, Bighetti EJ, de Faria EC , Degaspari GR, Souza CT, Vercesi AE (2003) Hypertriglyceridemia increases mitochondrial resting respiration and susceptibility to permeability transition. J. Bioenerg. Biomembr. 35: 451-457.


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