Sulfonylureas exert their hypoglycemic effect by binding to specific receptors and inhibiting ATP-modulated K+ channels in insulin-secreting cells.
Sulfonylureas are powerful hypoglycemic drugs that have been used for decades to treat diabetic patients. This paper describes a 86Rb+ flux technique that permits one to study easily the properties of ATP-modulated K+ channels in RINm5F insulinoma cells. Sulfonylureas inhibit this type of K+ channel under conditions of intracellular ATP depletion. The most potent sulfonylureas (glibenclamide, glipizide, and gliquidone) are acting in the nanomolar range of concentration. Inhibition of the single ATP-modulated K+ channels by low concentrations of sulfonylureas was also observed using the patch-clamp technique. The sulfonylurea receptor has been biochemically identified with 3Hglibenclamide. For 10 different sulfonylureas (or sulfonylurea analogs) there was an excellent correlation between efficacy of blockade of ATP-modulated K+ channels and efficacy of binding to the sulfonylurea receptors using the 3H-ligand.
Schmid‐Antomarchi et al. (Sun,) studied this question.