GLIBENCLAMIDE RELAXES VASCULAR SMOOTH-MUSCLE CONSTRICTION PRODUCED BY PROSTAGLANDIN-F2-ALPHA

The present study has demonstrated: (1) glibenclamide can reduce resting tension in canine cerebral arteries but has no effect on resting tension in the rat aorta; (2) glibenclamide can relax prostaglandin F2-alpha-induced contractions in the rat aorta, and in canine femoral, mesenteric, renal, coronary, basilar and middle cerebral arteries; (3) the relaxation produced by glibenclamide in rat aorta is comparable to that of glyceryl trinitrate and stronger than that of papaverine; (4) canine femoral arteries are less sensitive to glibenclamide than the other arteries; (5) in cerebral arteries glibenclamide was as effective as papaverine, but less effective than glyceryl trinitrate; (6) the actions of glibenclamide on cerebral arteries are not mediated by cGMP as they were not blocked by methylene blue, an inhibitor of guanylate cyclase; (7) the effects of glibenclamide are not endothelium-dependent. The mechanism by which glibenclamide produces relaxation is not clear; while the drug is known to block ATP-dependent potassium channels, in vascular smooth muscle this would cause contraction, not dilation. The action of glibenclamide may be at the level of the receptor or the signal transduction process.