%0 Journal Article
%T Fusion of the Endoplasmic Reticulum and Mitochondrial Outer Membrane in Rats Brown Adipose Tissue: Activation of Thermogenesis by Ca2+
%A Leopoldo de Meis
%A Luisa A. Ketzer
%A Rodrigo Madeiro da Costa
%A Ivone Rosa de Andrade
%A Marlene Benchimol
%J PLOS ONE
%D 2012
%I Public Library of Science (PLoS)
%R 10.1371/journal.pone.0009439
%X 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 ¦ÌM. The activation of respiration was less pronounced than that of heat production. Heat production and ATP synthesis were inhibited by rotenone and KCN.
%U http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0009439