Biosynthesis of Immunoreactive Insulin by the Duct-Tied Dog Pancreas ∗

Abstract

Summary

“Acinar free” pancreata have been prepared by ligating the pancreatic ducts of dogs under sterile conditions and allowing the acinar portion of the pancreas to degenerate over the succeeding 8 weeks. Three pancreata were minced together for each incubation, and the pooled mince was divided into three equal aliquots. One aliquot served as the control, one was incubated with STH, and one with DNP. The ¹⁴C labeled amino acids were added to the incubation mixture and the tissues were incubated for 4 hours. Insulin activity was extracted from each tissue and medium and concentrated on Sephadex G-50 columns. Assay for ¹⁴C, IRI, and ILA indicated that the greatest amount of IRI and ILA was found in the fraction from the column that eluted in the same position as crystalline insulin. This fraction in the control and STH tissues had an appreciable amount of ¹⁴C. It is concluded that the duct-tied pancreas preparation is a useful model to study insulin biosynthesis. The presence of STH did not alter the ¹⁴C incorporation or the recovery of IRI or ILA in this preparation.