Inactivation of Insulin by the Isolated Liver of the Bullfrog

¹ From the Departments of Medicine, Jewish Chronic Disease Hospital, Brooklyn, and State University of New York Medical Center, New York City

Experiments are presented in which insulin solutions were perfused through isolated frog livers in order to study the inactivation of this hormone by liver tissue. The solutions were recirculated many times and aliquots were tested biologically at various intervals for hypoglycemic activity. While insulin retains its activity after a single frog liver perfusion, it is gradually inactivated with increasing numbers of reperfusions. This result is in accord with the inactivation of insulin by liver slices and liver brei as reported by others. The relatively slow inactivation of insulin when perfused through the isolated frog liver is in contrast to the inactivation of glucagon which, as previously reported, loses its hyperglycemic activity after a single perfusion through this preparation. The general significance of this finding is discussed.