A method for studying the enteroinsular axis in unanesthetized and unrestrained rats

A method for studying the enteroinsular axis of rats under conditions comparable to those in experiments on human subjects was developed by chronically implanting an oral tube and two cardiac catheters into rats. These implantations were easy to perform and made it possible to give glucose and other stimulatory agents orally and/or intravenously and to take sequential blood samples without anesthetizing the rats or disturbing their movements. In this way, it was possible to confirm that oral loads of glucose and fat potentiate the insulin response induced by hyperglycemia.