Abstract: Two groups of vascular strips were prepared with aorta thorcalis of the rat.The vascu-lar endothelium was intact in one group and removed in the other.The two types of prepara-tions were superfused with Tyrod's solution.Under the background of the vascular contrac-tion induced by NE(10^-7 mol/L) or high K⁺ (50 mmol/L) bear bile caused a similar,dose-dependent relaxation in both groups.Bear bile of 0.5 mg/L could completely counteract the vascular contraction induced by NE but reduced the developed tension,caused by perfusate containing K⁺ of 50 mmol/L by 50%.The relaxant effect of bear bile in both groups of vas-cular strips were not significant(P>0.1).This study suggested that the relaxant effect of bear bile on the blood vessel was not depended on the presence of the vascular endothelium.

Key words: thoracic aorta, bear bile, vascular endothelium, high K, norepinephrine