The role of glucagon in the regulation of myocardial lipoprotein lipase activity

The role of glucagon in regulating the lipoprotein lipase activities of rat heart and adipose tissue was examined. When starved rats were fed glucose, heart lipoprotein lipase activity decreased while that of adipose tissue increased. Glucagon administration to these animals at the time of glucose feeding prevented the decline in heart lipoprotein lipase activity, but had no effect on the adipose tissue enzyme. When glucagon was administered to fed rats, heart lipoprotein lipase activity increased to levels found in starved animals but there was no change in the adipose tissue enzyme. It is suggested that the reciprocal lipoprotein lipase activities in heart and adipose tissue of fed and starved animals may be regulated by the circulating plasma insulin and glucagon concentrations.