The effect of cold exposure on liver mitochondrial and peroxisomal distribution in the rat, hamster and bat

Abstracto1.Liver mitochondrial number and size and peroxisomal number were compared in: control and cold-acclimated rats; control and hibernating hamsters; control, torpid and aroused bats.2.In the rodents, cold exposure led to increased mitochondrial number, peroxisomal number, and total amount of liver mitochondrial material (calculated as mitochondrial number times size).3.In the bat, cold exposure yielded more, but smaller mitochondria with no increased total mitochondrial material. Additionally, peroxisomal numbers decreased.4.The increased rodent mitochondrial material may reflect an enhanced thermogenic potential resulting from increased metabolic machinery, while the peroxisomal increase supports their proposed calorigenic function. However, peroxisomal thermogenesis remains to be quantitatively evaluated.