Phosphofructokinase activity in the brown fat, liver and heart of hibernating and homeothermic thirteen-lined ground squirrels (Citellus tridecemlineatus)

1.1. Phosphofructokinase activity in the brown fat of the thirteen-lined ground squirrel was found to be 6-fold lower during the time of hibernation than during the period of activity in the summer months.2.2. Phospnofructokinase activity m the heart and liver were not found to be significantly altered.3.3. It is suggested that the relative importance of glycolysis declined during hibernation in the brown fat and that glycolysis in the heart and liver was unaltered.