Fasting and postprandial GIP values in pigs, rats, dogs, and man measured with five different GIP antisera.

Fasting and postprandial blood samples were collected from pigs, rats, dogs, and man and the gastric inhibitory polypeptide (GIP) immunoreactivity measured with five different antisera. The mean GIP values in rats, dogs, and man varied considerably, depending on the antiserum used, whereas all the antisera recorded fairly similar GIP values in pigs. These findings demonstrate immunological differences between rat, dog, human, and porcine GIP. One should therefore be careful when evaluating physiological effects of porcine GIP infused intravenously in species other than the pig.