Cystic Fibrosis Research Laboratory, Stanford Univ., CA 94305-2130, USA.
Am J Physiol Lung Cell Mol Physiol. 2011 Mar;300(3):L370-9. doi: 10.1152/ajplung.00372.2010. Epub 2010 Dec 3.
Human and pig airway submucosal glands secrete mucus in response to substance P (SubP), but in pig tracheal glands the response to SubP is >10-fold greater than in humans and shares features with cholinergically produced secretion. CFTR-deficient pigs provide a model for human cystic fibrosis (CF), and in newborn CF pigs the response of tracheal glands to SubP is significantly reduced (Joo et al. J Clin Invest 120: 3161-3166, 2010). To further define features of SubP-mediated gland secretion, we optically measured secretion rates from individual adult porcine glands in isolated tracheal tissues in response to mucosal capsaicin and serosal SubP. Mucosal capsaicin (EC(50) = 19 μM) stimulated low rates of secretion that were partially inhibited by tetrodotoxin and by inhibitors for muscarinic, VIP, and SubP receptors, suggesting reflex stimulation of secretion by multiple transmitters. Secretion in response to mucosal capsaicin was inhibited by CFTR(inh)-172, but not by niflumic acid. Serosal SubP (EC(50) = 230 nM) stimulated 10-fold more secretion than mucosal capsaicin, with a V(max) similar to that of carbachol. Secretion rates peaked within 5 min and then declined to a lower sustained rate. SubP-stimulated secretion was inhibited 75% by bumetanide, 53% by removal of HCO(3)(-), and 85% by bumetanide + removal of HCO(3)(-); it was not inhibited by atropine but was inhibited by niflumic acid, clotrimazole, BAPTA-AM, nominally Ca(2+)-free bath solution, and the adenylate cyclase inhibitor MDL-12330A. Ratiometric measurements of fura 2 fluorescence in dissociated gland cells showed that SubP and carbachol increased intracellular Ca(2+) concentration by similar amounts. SubP produced rapid volume loss by serous and mucous cells, expansion of gland lumina, mucus flow, and exocytosis but little or no contraction of myoepithelial cells. These and prior results suggest that SubP stimulates pig gland secretion via CFTR- and Ca(2+)-activated Cl(-) channels.
人类和猪的气道黏膜下腺会对 P 物质（SubP）做出分泌反应，但在猪的气管腺中，对 SubP 的反应是人类的 10 倍以上，并且具有胆碱能产生的分泌特征。CFTR 缺陷型猪提供了人类囊性纤维化（CF）的模型，在新生 CF 猪的气管腺对 SubP 的反应明显降低（Joo 等人，J Clin Invest 120: 3161-3166，2010）。为了进一步定义 SubP 介导的腺体分泌的特征，我们在离体气管组织中使用光学方法测量了单个成年猪腺的分泌速率，以响应黏膜辣椒素和浆膜 SubP。黏膜辣椒素（EC（50）= 19 μM）刺激低分泌速率，被河豚毒素和用于毒蕈碱、VIP 和 SubP 受体的抑制剂部分抑制，表明多种递质的反射性刺激分泌。黏膜辣椒素引起的分泌被 CFTR(inh)-172 抑制，但不受 niflumic acid 抑制。浆膜 SubP（EC（50）= 230 nM）刺激的分泌比黏膜辣椒素多 10 倍，与 carbachol 的 V（max）相似。分泌速率在 5 分钟内达到峰值，然后下降到较低的持续速率。SubP 刺激的分泌被 bumetanide 抑制 75%，HCO（3）（-）去除抑制 53%，bumetanide + HCO（3）（-）去除抑制 85%；它不受阿托品抑制，但受 niflumic acid、clotrimazole、BAPTA-AM、名义上无 Ca（2+）的浴液和腺苷酸环化酶抑制剂 MDL-12330A 抑制。在分离的腺细胞中 fura 2 荧光的比率测量表明，SubP 和 carbachol 增加细胞内 Ca（2+）浓度的量相似。SubP 通过浆液和黏液细胞迅速导致体积损失，扩大腺腔、黏液流动和胞吐作用，但对肌上皮细胞几乎没有或没有收缩作用。这些和先前的结果表明，SubP 通过 CFTR 和 Ca（2+）激活的 Cl（-）通道刺激猪的腺体分泌。
