Development of Response to Glucose of Fetal Rat Islet in Organ Culture 1

Abstract

Summary

Pancreases of 18-day fetal and 3-day neonatal rat were grown in organ culture in both standard glucose (150 mg/100 ml) and high glucose (500 mg/100 ml) media. Insulin content of medium was measured by radioimmunoassay at time of transfer.

In fetal cultures, standard and high glucose media contained a similar level of insulin through 6 days of culture. In neonatal cultures, high glucose medium contained 40-60% more insulin than did standard medium. However, after 8 days of organ culture fetal pancreas developed responsiveness to high glucose; a greater amount of insulin was present in the high glucose medium (50% by 10 days and 70% by 12 days) than in standard glucose medium. The time at which this responsiveness develops in vitro approximates the chronologic age which corresponds to 3-5 days postnatal period. The maturation of this responsiveness appears to be inherent to the pancreas and is independent of other organ systems.

When neonatal explants, grown in standard medium for 8 days, were transferred to high glucose medium, 80-160% more insulin was detected in the high glucose medium than in standard medium during the next 4 days of culture. These results indicate that once glucose responsiveness has developed, it is maintained in organ culture for at least 12 days.