Relationship between structure and function of liver mitochondria from hibernating and active ground squirrels, Citellus undulatus.

1. Electron microscopy of liver tissue preparations, obtained from hibernating ground squirrels, reveals mitochondria in a condensed state. 2. When kept on ice, mitochondria isolated from the livers of hibernating and active ground squirrels are in a shrunken state. 3. Incubation of mitochondria isolated from the livers of active ground squirrels in the presence of succinate, at 27 degrees C, results in mitochondrial swelling, while mitochondria from hibernating ground squirrels under the same conditions remain relatively shrunken. 4. The swollen mitochondria from active ground squirrels show high oxidative activity, while the shrunken mitochondria from hibernating animals show low oxidative activity. 5. Swelling of mitochondria from hibernating ground squirrels in a hypo-osmolar medium is accompanied by a significant increase in oxidative activity. 6. It is inferred that the shrinkage of hibernating ground squirrel mitochondria is one of the main causes of the inhibition of oxidative activity and other mitochondrial functions during hibernation.

Seasonal variations of DNA synthesis in intestinal epithelial cells of hibernating animals--I. DNA synthesis in intestinal epithelial cells of ground squirrel (Citellus undulatus) during deep hibernation.

The conditions for obtaining crypt cells from ground squirrel small intestine were chosen which allow flow-through cytofluorometric analysis of the DNA synthesis of this tissue. DNA synthesis was found to be greatly reduced in the intestinal crypt cells of ground squirrel during deep hibernation in torpid animals, in animals during spontaneous arousals and in animals prevented from hibernation. The conclusion is made about endogenous control of the DNA synthesis in the cells of true hibernators.