Effects of Bay K 8644 on the Electrically Evoked and KCI-Evoked Norepinephrine Release and the Corresponding Contraction in Isolated Canine Saphenous Veins

Abstract

Bay K 8644 caused no significant effects on the ³H overflow and contraction evoked by electrical stimulation in the canine saphenous vein preloaded with [³H]norepinephrine. Bay K 8644 significantly enhanced the ³H overflow evoked by 40 mM KCl in a concentration-dependent manner, which was antagonized by nisoldipine. Bay K 8644 failed to significantly augment the KCl-evoked contraction. These results suggest that there is a difference between the modes of action of Bay K 8644 on norepinephrine releases evoked by electrical stimulation and KCl.