摘要
气道上皮释放抑制因子,如一氧化氮(NO)和前列腺素E2 (PGE2),可抵消支气管收缩。我们研究了上皮来源的抑制物质是否对体外牛气管反应性有重要影响。比较了完整和上皮剥去的气管平滑肌条对组胺反应的等张和等长收缩。此外,还研究了l -精氨酸(L-arg)、N(G)-硝基- l -精氨酸甲基艾斯特(L-NAME)和N(G)-单甲基l -精氨酸(L-NMMA)对组胺反应性的影响。测定气管上皮释放NO和PGE2。从气管平滑肌条中去除上皮并没有改变产生最大效应的一半(pD2)或最大效应(Emax)的组胺浓度的负对数。用L-arg或L-NAME孵育组织25分钟不影响基础张力或组胺引起的收缩。然而,与L-NMMA孵育增加基础色调和引起轻微低反应组胺。s -亚硝基-n -乙酰青霉胺(SNAP,一种直接NO供体)以浓度依赖的方式逆转组胺引起的收缩。与基础水平相比,0.1 microM组胺刺激上皮层使NO释放增加3-4倍; this effect was completely inhibited in the presence of L-NMMA. In addition, 1 mM histamine caused a significant increase in the release of PGE2 from the epithelial tissue. In conclusion, no functional inhibitory influence of the epithelium can be identified in bovine airways. The S-nitroso-N-acetyl-penicillamine-induced relaxation demonstrates the presence of a nitric oxide sensitive pathway in bovine airways. However, the amounts of nitric oxide and prostaglandin E2 released from bovine tracheal epithelium are probably too low to exert a significant effect on the histamine-induced contractions.