VASODILATIVE PROPERTIES OF BPDZ-79, A NEW POTASSIUM CHANNEL OPENER, IN ISOLATED AORTA

AIM: To compare the effect of a novel potassium channel opener 3-(1',2 ',2'-trimethylpropyl) amine-4H- pyrido (2,3-e)-1,2,4- thiadiazine, 1- dioxide (BPDZ 79), with diazoxide on aorta. METHODS: Muscle tension of rat aorta was compared with adjacent aortic rings without endothelium . One ring was precontracted with KCl 80 mmol . L(-1) Three rings were precontracted with KCl 30 mmol . L(-1), and two of them were incubate d with glibenclamide (0, 1, and 10 mu mol . L(-1)). Rb-86 outflow from rat aorta was measured in the presence of glibenclamide 10 mu mol . L (-1). RESULTS: BPDZ 79 and diazoxide provoked concentration-dependent and endothelium-independent relaxation of the vasoconstriction evoked by KCL 30 mmol . L(-1), but not by 80 mmol . L(-1). BPDZ 79 showed mor e potent vasorelaxation and Rb-86 out-flow than diazoxide. After incub ation with glibenclamide (1 and 10 mu mol . L(-1)), an inhibitor of th e ATP-sensitive K+ channels, the relaxation induced by BPDZ 79 and dia zoxide were decreased with the same pattern. CONCLUSION: BPDZ 79 is a potent vasodilator by opening potassium channels.