Effect of experimental diabetes and glucagon on cAMP-dependent protein kinase in rat liver.

Liver protein kinase was determined in the absence and presence of cAMP4. Experimental alloxan diabetes resulted in a decrease in total protein kinase (+cAMP) and an increase in the activity ratio (-cAMP) divided by (+cAMP) in liver. Insulin treatment of diabetic rats reversed the observed changes in protein kinase in liver. Glucagon administered in vivo to normal rats caused an increase in the activity ratio and a decrease in total protein kinase activity in liver. The changes are similar to those in diabetes. A decrease in the ratio of insulin to glucagon in diabetes may account for the changes in protein kinase observed.