VASOSPASMOLYTIC EFFECT OF KRN2391 ON 3,4-DIAMINOPYRIDINE-INDUCED RHYTHMIC CONTRACTION OF PORCINE CORONARY-ARTERY

1. In the present study, we examined the vasospasmolytic effect of KRN 2391 on rhythmic contractions of porcine coronary artery caused by 3,4 -diaminopyridine (3,4-DAP) cromakalim and nitroglycerin. 2. KRN2391 at 10(-7) showed a tendency to prolong the cycle length and at 10 elimin ated rhythmic contractions in all preparations. The elimination by 10( -6) M antagonized by either oxyhemoglobin (10(-5) M) or glibenclamide (3 x 10(-6)) although 3. Cromakalim at 10(-5) M and nitroglycerin at 1 0(-7) M completely eliminated 3,4-DAP-induced rythmic contractions in all preparations. The elimination by cromakalim and nitroglycerin was completely antagonized by glibenclamide and oxyhemoglobin, respectivel y. 4. The present study suggests that the vasospasmolytic effect of KR N2391 on 3,4-DAP-induced rhythmic contractions is based on its nitrate action and K channel opening action.