The oral hypoglycemic agent, U-56324, inhibits the activity of ATP-sensitive potassium channels in cell-free membrane patches from cultured mouse pancreatic B-cells.

U-56324, a hypoglycemic agent derived from nicotinic acid, inhibited the activity of ATP-sensitive potassium channels in excised patches from mouse pancreatic B-cells. The effect of U-56324 on channel activity was reversible and concentration-dependent while it had no effect on single channel conductance. The positional isomer, U-59588, which has relatively little hypoglycemic activity, had no effect on channel properties. U-56324, at the same concentrations, had no effect on calcium-activated potassium channels. The basis for the potentially antidiabetic properties of U-56324 may therefore be due to direct and specific inhibition of ATP-sensitive potassium channels.