De Meis 2010 PLoS One

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De Meis L, Ketzer LA, da Costa RM, de Andrade IR, Benchimol M (2010) Fusion of the endoplasmic reticulum and mitochondrial outer membrane in rats brown adipose tissue: activation of thermogenesis by Ca2+. PLoS One 5:e9439.

» PMID: 20209153 Open Access

De Meis L, Ketzer LA, da Costa RM, de Andrade IR, Benchimol M (2010) PLoS One

Abstract: Brown adipose tissue (BAT) mitochondria thermogenesis is regulated by uncoupling protein 1 (UCP 1), GDP and fatty acids. In this report, we observed fusion of the endoplasmic reticulum (ER) membrane with the mitochondrial outer membrane of rats BAT. Ca2+-ATPase (SERCA 1) was identified by immunoelectron microscopy in both ER and mitochondria. This finding led us to test the Ca2+ effect in BAT mitochondria thermogenesis. We found that Ca2+ increased the rate of respiration and heat production measured with a microcalorimeter both in coupled and uncoupled mitochondria, but had no effect on the rate of ATP synthesis. The Ca2+ concentration needed for half-maximal activation varied between 0.08 and 0.11 µM. The activation of respiration was less pronounced than that of heat production. Heat production and ATP synthesis were inhibited by rotenone and KCN. Liver mitochondria have no UCP1 and during respiration synthesize a large amount of ATP, produce little heat, GDP had no effect on mitochondria coupling, Ca2+ strongly inhibited ATP synthesis and had little or no effect on the small amount of heat released. These findings indicate that Ca2+ activation of thermogenesis may be a specific feature of BAT mitochondria not found in other mitochondria such as liver.

Keywords: Brown adipose tissue, Ca2+-ATPase, mt-membrane potential, Respiration, Heat Production, ATP Synthesis

O2k-Network Lab: BR Rio de Janeiro Galina A


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Organism: Rat  Tissue;cell: Fat  Preparation: Isolated mitochondria  Enzyme: Marker enzyme, Uncoupling protein  Regulation: Fatty acid  Coupling state: OXPHOS 

HRR: Oxygraph-2k