Open AccessThe Acute Regulation of Mitochondrial Proton Conductance in Cells and Mitochondria from the Brown Fat of Cold‐Adapted and Warm‐Adapted Guinea Pigs
Author(s) -
LOCKE Rebecca M.,
RIAL Eduardo,
NICHOLLS David G.
Publication year - 1982
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1982.tb07061.x
Subject(s) - mitochondrion , brown adipose tissue , thermogenesis , respiration , biology , fatty acid , thermogenin , biochemistry , conductance , chemistry , adipose tissue , medicine , anatomy , mathematics , combinatorics
Cells and mitochondria were prepared from the brown adipose tissue of adult guinea‐pigs adapted to either 4–7°C or 22–25°C. The cold‐adapted cells displayed noradrenaline‐stimulated, propranolol‐sensitive respiration, but noradrenaline failed to increase the respiration of the warm‐adapted cells. Purine‐nucleotide‐sensitive proton conductance was greater in cold‐adapted mitochondria than in warm‐adapted controls. At the same time cold‐adapted mitochondria were extremely sensitive to the uncoupling effect of endogenous and infused fatty acids, and resembled the mitochondria from the brown adipose tissue of cold‐adapted hamsters. Warm‐adapted mitochondria were ninefold less sensitive, and resembled liver mitochondria. With cold‐adapted, but not warm‐adapted mitochondria, respiration increased proportionately to the rate of fatty acid infusion. It is concluded that the presence of the 32000‐ M r proton conductance pathway is necessary for the expression of a high sensitivity to fatty acid uncoupling, suggesting that the fatty acids interact directly with this protein to modulate the proton conductance during the acute regulation of thermogenesis.