Decrease of oxidative activities in brown adipose tissue mitochondria of cold acclimated rats on short term exposure to heat stress

Gaikwad, Amos S and Ramasarma, T and Kurup, Ramakrishna CK (1990) Decrease of oxidative activities in brown adipose tissue mitochondria of cold acclimated rats on short term exposure to heat stress. In: Biochimica et Biophysica Acta (BBA) - Bioenergetics, 1017 (3). pp. 242-250.

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Abstract

Exposure of rats to the cold $(4-5^0C)$ caused large (2-3-fold) increase in the mass of interscapular brown adipose tissue (BAT), its mitochondrial content and the basal metabolic rate of the animals. The rate of substrate oxidation by BAT mitochondria also increased about 3-fold. When cold-acclimated animals were exposed to heat $(37^0C)$, the BMR decreased by half in 3 h, the earliest time interval tested. Mitochondrial substrate oxidation, as well as substrate-dependent $H_2O_2$ generation, showed a proportionate decrease in rates. In these mitochondria, activities of cytochrome c reductases, but not dehydrogenases with NADH, $\alpha$-glycerophosphate and succinate as substrates, also showed a significant decrease. The concentration of cytochromes $aa_3$ and b, but not cytochrome c, also decreased in BAT mitochondria from 12-h heat-exposed animals, while the change in concentration of cytochrome b alone was found as early as 3 h of heat exposure. These results identify the change in cytochromes as a mechanism of regulation of oxidative activities in BAT mitochondria under conditions of acute heat stress.

Item Type:	Journal Article
Publication:	Biochimica et Biophysica Acta (BBA) - Bioenergetics
Publisher:	Elsevier Science B.V.
Additional Information:	Copyright of this article belongs to Elsevier Science B.V.
Keywords:	Brown adipose tissue mitochondria;Electron transport;Cytochrome b;Hydrogen peroxide generation;Basal metabolic rate
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	21 Feb 2008
Last Modified:	19 Sep 2010 04:41
URI:	http://eprints.iisc.ac.in/id/eprint/12663

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