Chander A, Sen N
Institute for Environmental Medicine, University of Pennsylvania, School of Medicine, Philadelphia 19104.
Biochem Pharmacol. 1993 May 5;45(9):1905-12. doi: 10.1016/0006-2952(93)90450-b.
Various agents stimulate the secretion of lung surfactant from alveolar type II cells by increasing intracellular Ca2+, cyclic adenosine-3':5'-monophosphate (cAMP), or diacylglycerol. A few agents, including the purified surfactant protein A, are known to inhibit the secretion by an unknown mechanism. In the present study, we demonstrated that stilbene disulfonic acids, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) and 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid (SITS), are potent but reversible inhibitors of lung surfactant secretion. The inhibition was concentration dependent, and the EC50 was 5 microM for DIDS and 50 microM for SITS. The inhibition was not specific to agonists for any one type of receptor, and was also observed for secretion stimulated by 8-bromo-cAMP, or tetradecanoyl phorbol acetate, suggesting that the site of inhibition was distal to the generation of intracellular second messengers. This was also supported by the failure of DIDS to block the stimulus-mediated increase in diacylglycerol content of type II cells. Further, DIDS and SITS were also inhibitory for basal secretion. Based on the reversibility of inhibition and the fact that inhibition was observed with both basal and stimulated secretion, we suggest that stilbene disulfonic acids affect a component of the exocytosis process that occurs at or near the plasma membrane.
多种因子通过增加细胞内钙离子、环磷酸腺苷（cAMP）或二酰基甘油来刺激肺泡Ⅱ型细胞分泌肺表面活性物质。已知包括纯化的表面活性蛋白A在内的一些因子可通过未知机制抑制分泌。在本研究中，我们证明了二苯乙烯二磺酸、4,4'-二异硫氰酸根合芪-2,2'-二磺酸（DIDS）和4-乙酰氨基-4'-异硫氰酸根合芪-2,2'-二磺酸（SITS）是肺表面活性物质分泌的强效但可逆的抑制剂。抑制作用呈浓度依赖性，DIDS的半数有效浓度（EC50）为5微摩尔，SITS为50微摩尔。这种抑制作用并非针对任何一种受体的激动剂具有特异性，对于8-溴-cAMP或十四酰佛波醇乙酸酯刺激的分泌也有观察到，这表明抑制位点在细胞内第二信使产生的下游。DIDS未能阻断刺激介导的Ⅱ型细胞二酰基甘油含量增加也支持了这一点。此外，DIDS和SITS对基础分泌也有抑制作用。基于抑制作用的可逆性以及在基础分泌和刺激分泌中均观察到抑制这一事实，我们认为二苯乙烯二磺酸影响了发生在质膜或其附近的胞吐过程的一个组分。
