Hibernation: alteration of mitochondrial membranes as a requisite for metabolism at low temperature.

Lipids of mitochondrial membranes from hepatic cells of active ground squirrels apparently go through a phase change induced at approximately 23 degrees C similar to the phase change in mitochondria of homeotherms. This change was indicated by the activity of succinate oxidase from the isolated mitochondria exhibiting a nonintersecting discontinuous Arrhenius plot. This discontinuity in the Arrhenius plot is not evident with mitochondria from the livers of hibernating squirrels, which indicates that the temperature-induced phase change in the mitochondrial membranes has been eliminated. These findings suggest that physical properties of the mitochondrial membrane change in relation to the process of hibernation.