title: Palmitate potentiation of glucose-induced insulin release: a study using 2-bromopalmitate.
abstract: The mechanisms whereby fatty acids (FA) potentiate glucose-induced insulin secretion from the pancreatic beta cell are incompletely understood. In this study, the effects of palmitate on insulin secretion were investigated in isolated rat islets. Palmitate did not initiate insulin secretion at nonstimulatory glucose concentrations, but markedly stimulated insulin release at concentrations of glucose > or = 5.6 mmol/L. At concentrations of palmitate > or =0.5 mmol/L, the important determinant of the potency of the FA was its unbound concentration. At total concentrations < or = 0.5 mmol/L, both the total and unbound concentrations appeared important. Surprisingly, 2-bromopalmitate did not affect palmitate oxidation, but significantly diminished palmitate esterification into cellular lipids. Neither methyl palmitate, which is not activated into a long-chain acyl-CoA ester, nor 2-bromopalmitate affected glucose-stimulated insulin release. Further, 2-bromopalmitate partly inhibited the potentiating effect of palmitate. These results support the concept that FA potentiation of insulin release is mediated by FA-derived signals generated in the esterification pathway.
authors.affiliation: Pacific Nortwest Research Institute, Seattle, WA 98122, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Parker
authors.forename: P C
authors.initials: PC
authors.lastname: Moore
authors.forename: L M
authors.initials: LM
authors.lastname: Johnson
authors.forename: V
authors.initials: V
authors.lastname: Poitout
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D004357:Drug Synergism; D004951:Esterification / Q000187:drug effects; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D050356:Lipid Metabolism; D008297:Male; D010084:Oxidation-Reduction / Q000187:drug effects; D010168:Palmitates / Q000008:administration & dosage / Q000378:metabolism* / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D010168:Palmitates; C022776:2-bromopalmitate