Antidiabetic sulfonylureas relax isolated rabbit coronary arteries.

Antidiabetic sulfonylureas completely relaxed isolated rabbit coronary arteries contracted by prostaglandin F2 alpha. The order of potency was glibenclamide (EC50 = 4.75 microM) greater than glipizide = glibornuride = tolbutamide = chlorpropamide. The drugs also relaxed the contractions induced by 30 mM K+ but much less potently. The effectiveness of the drugs as vascular smooth muscle relaxants did not correlate with their ability to antagonize the vasorelaxant action of cromakalim. Sulfonylurea-induced vasorelaxation probably involves mechanisms other than an interaction with ATP-regulated K+ channels.