1. In rats in a variety of nutritional states, the adipose tissue clearing factor lipase activity is strongly, positively correlated with fat-cell triglyceride fatty acid uptake.
2. In the same animals, muscle clearing factor lipase activity is inversely correlated with the activity of the enzyme in adipose tissue and with the plasma insulin concentration.
3. In starved animals that are given glucose, adipose tissue clearing factor lipase activity is positively correlated with the plasma insulin concentration.
4. The effect of changes in nutritional status on the activity of clearing factor lipase in rat post-heparin plasma depends on the heparin dosage used. The administration of glucose, but not of fructose or sucrose, to starved rats alters the response to heparin injection towards that found in rats in the fed state.