Studies on the N-[(trans-4-isopropylcyclohexyl)-carbonyl]-D-phenylalanin E (A-4166)receptor in HIT T-15 Cells. Displacement of [3H]glibenclamide

Biochem Pharmacol. 1996 Aug 9;52(3):407-11. doi: 10.1016/0006-2952(96)00242-0.

Abstract

A-4166 is a new type of oral hypoglycemic agent that does not contain a sulfonylurea moiety. To clarify the mechanism of insulin secretion by A-4166, a specific receptor for A-4166 was investigated in a hamster pancreatic beta cell line (HIT T-15), using [3H]A-4166 or [3H]glibenclamide as a ligand. The saturation binding of [3H]A-4166 to HIT cell membranes was not observed up to 10 microM. In the displacement study, unlabeled A-4166 inhibited [3H]A-4166 binding to HIT cell membranes, but glibenclamide did not. On the other hand, A-4166 inhibited [3H]glibenclamide binding to the sulfonylurea receptor (Ki = 248 nM). A-4166 inhibited 86Rb efflux from HIT cells (IC50 = 350 nM). The EC50 for insulin secretion by A-4166 was 20 microM in HIT cells when they were incubated for 30 min in Krebs-Ringer bicarbonate buffer containing 16 mM HEPES supplemented with 5 mg/mL BSA in the absence of glucose. These data demonstrate the possibility of the presence of two kinds of binding sites for A-4166: one of them is the sulfonylurea receptor, and the other might be a binding site specific for A-4166.

MeSH terms

  • Animals
  • Binding Sites
  • Cricetinae
  • Cyclohexanes / metabolism*
  • Dose-Response Relationship, Drug
  • Glyburide / metabolism*
  • Hypoglycemic Agents / metabolism*
  • Mice
  • Nateglinide
  • Phenylalanine / analogs & derivatives*
  • Phenylalanine / metabolism
  • Radioligand Assay

Substances

  • Cyclohexanes
  • Hypoglycemic Agents
  • Nateglinide
  • Phenylalanine
  • Glyburide