EFFECT OF GLUCOSE AND AMINO ACIDS ON FOETAL RAT PANCREATIC GROWTH AND INSULIN SECRETION IN VITRO

SUMMARY Foetal rat pancreatic rudiments explanted on day 14 of gestation were grown for 6 days in organ culture in medium containing glucose (5·5 or 16·5 mmol/l) and amino acids at the 'physiological' or seven times the 'physiological' concentration. At the end of the period of culture, the rudiments were compared with normal 20-day foetal pancreas for DNA content, insulin concentration and quantitative morphology. The secretion of insulin from the explants was tested during 2 h incubations in medium containing glucose (5·5 or 16·5 mmol/l). Amino acid, but not glucose enrichment of the culture medium stimulated cellular growth of the rudiment which remained, nevertheless, smaller than that occurring in vivo. All culture conditions produced a smaller proportion of exocrine cells and a greater proportion of β and duct cells than were found in normal 20-day foetal pancreas. Enrichment with amino acids favoured the development of exocrine cells at the expense of duct cells. Glucose had no effect on the development of any type of cell. Enrichment with amino acids resulted in a higher concentration of insulin per β cell but the highest value observed in vitro was only one sixth of that occurring in vivo. The absolute number of β cells cultured in amino-acid-enriched medium was twice that occurring in vivo. Culture in a glucose-enriched medium had no effect on the ability of the explant to respond to an acute glucose challenge during a short incubation, but the basal and glucose-stimulated release of insulin from cultures grown in amino-acid-enriched medium were significantly greater.