Glibenclamide does not block arterial relaxation caused by vasoactive intestinal polypeptide.

Vasoactive intestinal polypeptide (VIP) caused a concentration-dependent relaxation in rabbit mesenteric artery with intact endothelium. The relaxant response to VIP was inhibited by the removal of the endothelium or by pretreatment with methylene blue, but not by pretreatment with glibenclamide. A small but significant relaxant response to VIP in the endothelium-denuded artery was also unaffected by glibenclamide. These findings indicate that ATP-sensitive K+ channels are not involved in the endothelium-dependent or endothelium-independent arterial relaxation elicited by VIP.