Blood glucose levels in portal and peripheral circulation and their relation to food intake in the rat.

Rats weighing about 450 g were provided with permanent catheters in the portal vein and the right auricle. This method allows blood sampling from the portal and peripheral circulation at the same moment in the nondisturbed unanesthetized rat. In the ad lib condition the portal glucose level was higher than that in the general circulation before, during, and after the meal. After a fast of 22 hr premeal portal vein levels were equal to those of the general circulation. During the meal the portal glucose levels rose to about 150 mg per 100 ml whereas those of the general circulation did not exceed 130 mg/100 ml. Experiments with glucose infusions systemically and intraportally show that, under conditions of mild deprivation, the level of glucose in the portal vein plays no or only a very minor role in the termination of feeding.