Characterization of insulin glycation in insulin-secreting cells maintained in tissue culture.
Characteristics of cellular insulin glycation were examined in the pancreatic B-cell line, BRIN-BD11. The extent of insulin glycation increased stepwise during 72 h of culture at 5.6-33.3 mmol/l glucose, attaining levels up to 27%. Glycation of insulin at 33.3 mmol/l glucose was rapid, reaching maximal values within 2 h, and not readily reversible during 2 to 24 h of subsequent exposure to 5.6 mmol/l glucose. Glycated insulin was readily secreted by BRIN-BD11 cells upon active stimulation with glucose and other secretagogues. Cellular insulin glycation was decreased by 66-80% by inhibitors of protein glycation, vitamin C, aminoguanidine or acetylsalicylic acid. Modulation of insulin-secretory activity of BRIN-BD11 cells by co-culture at high glucose with diazoxide. L-alanine or glibenclamide indicated that long-term stimulation of secretion was associated with a decrease in the extent of insulin glycation. Glycation of insulin in vitro was substantially less extensive than in BRIN-BD11 cells, although glucose-6-phosphate and glyceraldehyde-3-phosphate were 1.4- to 2.0-fold more reactive than glucose per se. These observations indicate that insulin is readily glycated and secreted from insulin-secreting cells under hyperglycaemic conditions in culture.
Abdel-Wahab
Y H
YH
School of Biomedical Sciences, University of Ulster, Coleraine, County Londonderry, UK.
O'Harte
F P
FP
Barnett
C R
CR
Flatt
P R
PR
D001205:Ascorbic Acid / Q000494:pharmacology; D001241:Aspirin / Q000494:pharmacology; D002460:Cell Line; D003981:Diazoxide / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D005905:Glyburide / Q000494:pharmacology; D006031:Glycosylation / Q000187:drug effects; D006146:Guanidines / Q000494:pharmacology; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism*; D013268:Stimulation, Chemical; D013997:Time Factors
D004791:Enzyme Inhibitors; D006146:Guanidines; D007004:Hypoglycemic Agents; D007328:Insulin; D005947:Glucose; D003981:Diazoxide; D001205:Ascorbic Acid; D001241:Aspirin; C004479:pimagedine; D005905:Glyburide