Mitochondrial heat production: the elephant in the lab…

It has long been established that heat represents a major part of the energy released during the oxidation of mitochondrial substrates. However, with a few exceptions, the release of heat is rarely mentioned other than as being produced at the expense of ATP, without having any specific function. Here, after briefly surveying the literature on mitochondrial heat production, we argue for its cellular and organismal importance, sharing our opinions as to what could account for this unbalanced portrayal of mitochondrial energy transactions.