Desensitization of sulphonylurea- and nutrient-induced insulin secretion following prolonged treatment with glibenclamide

Functional effects of prolonged exposure to the sulphonylurea glibenclamide were examined in a popular clonal pancreatic p-cell line, denoted as BRIN-BD11. In acute 20-min incubations, 200 muM of tolbutamide or glibenclamide stimulated insulin release from non-depolarized and depolarized cells, which was dramatically reduced following 18-h culture with 100 muM glibenclamide. Sulphonylurea desensitization in non-depolarized cells was reversed following 6-36-h subsequent culture in the absence of glibenclamide. However, desensitization of insulinotropic effects of sulphonylureas in depolarized cells following glibenclamide culture and associated decline in cellular insulin content was not fully reversible. Culture with 100 muM glibenclamide also markedly reduced the acute insulinotropic actions of glucose, L-alanine, L-arginine, 2-ketoisocaproic acid (KIC) and KCl. These effects were almost completely reversed following 18-h culture in the absence of the sulphonylurea. (C) 2000 Elsevier Science B.V. All rights reserved.