[Possible mechanisms for reduced endothelium dependent responsiveness to norepinephrine in isolated aorta of rats with peritonitis shock].

Various antagonists were used to analyze the possible factors contributing to the reduced endothelium-dependent response to norepinephrine in isolated aorta of rats with peritonitis shock. The concentration-effect curves to norepinephrine in the aortic rings with endothelium pretreated by methyl blue, atropine, anisodamine and indomethacin were shift to the left and the largest contraction was raised. The concentration-effect curve to norepinephrine was also shift to the left and the largest contraction was raised in the aortic ring with endothelium pretreated by propranolol. However, the similar changes were also observed in rings without endothelium pretreated by propranolol. While the concentration-effect curves to norepinephrine were shift to the right and the largest contraction reduced in rings with or without endothelium that pretreated by Yohimbine. The results suggested that the reduced endothelium-dependent responsiveness to norepinephrine in the isolated aorta of rats with peritonitis shock may involve various factors of which vasodilatation mediated by cGMP may be the one of importance.