Shiraishi S, Mori A, Toda N
Department of Pharmacology, Shiga University of Medical Science, Ohtsu, Japan.
Jpn J Pharmacol. 1993 Mar;61(3):243-50. doi: 10.1254/jjp.61.243.
The endothelium-dependency of vasodilator responses was compared in helical strips of canine internal thoracic (ITA) and coronary arteries partially contracted with serotonin. The addition of acetylcholine produced a concentration-related relaxation in ITA and coronary arterial strips with an intact endothelium. The relaxations were not influenced by indomethacin, but were markedly inhibited or abolished by methylene blue, NG-nitro-L-arginine (L-NA), a nitric oxide (NO) synthase inhibitor, and endothelial denudation. The responses to low concentrations of acetylcholine were significantly greater in ITA than in coronary arteries, whereas relaxations induced by substance P, Ca2+ ionophore (A23187) or NO in ITA were significantly less. The substance P-induced relaxation in ITA and coronary arteries was endothelium-dependent, and it was almost abolished by L-NA. Relaxations induced by ATP in ITA were abolished by endothelium denudation and treatment with L-NA. In the coronary arteries, relaxing responses were inhibited only partially by removal of endothelium and L-NA. Acetylcholine, ATP and substance P relax canine ITA possibly by a mediation of endothelium-derived NO, but not prostaglandin I2. Coronary arterial relaxations induced by ATP appear to be mediated by an indirect action via NO released from the endothelium, in addition to a direct action on the smooth muscle.
在使用血清素使犬类胸廓内动脉（ITA）和冠状动脉的螺旋条部分收缩的情况下，比较了血管舒张反应的内皮依赖性。添加乙酰胆碱后，完整内皮的ITA和冠状动脉条产生了浓度相关的舒张。这些舒张不受吲哚美辛影响，但被亚甲蓝、一氧化氮（NO）合酶抑制剂NG-硝基-L-精氨酸（L-NA）和内皮剥脱显著抑制或消除。低浓度乙酰胆碱引起的反应在ITA中比在冠状动脉中显著更大，而ITA中由P物质、Ca2+离子载体（A23187）或NO诱导的舒张则显著更小。P物质在ITA和冠状动脉中诱导的舒张是内皮依赖性的，并且几乎被L-NA消除。ITA中由ATP诱导的舒张被内皮剥脱和L-NA处理消除。在冠状动脉中，去除内皮和L-NA仅部分抑制舒张反应。乙酰胆碱、ATP和P物质可能通过内皮衍生的NO介导使犬类ITA舒张，但不是通过前列腺素I2。ATP诱导的冠状动脉舒张似乎除了对平滑肌的直接作用外，还通过内皮释放的NO的间接作用介导。
