Respiration of mitochondria from brown fat and the mechanism of thermogenesis

It is shown that both phosphorylating and nonphosphorylating (noncoupled) respirations, the latter being regulated by GDP and increasing in a series of substrates - pyruvate + malate----succinate----NADH----ascorbate(+ cytochrome c) have been presented in brown fat mitochondria of newborn guinea pigs and of adult rats under thermoneutral conditions. Noncoupled respiration is suggested to support thermogenesis not only under cold exposure but under thermoneutral conditions as well.