Gu Qihai, Lee Lu-Yuan
Department of Physiology, University of Kentucky Medical Center, 800 Rose Street, Lexington, KY 40536, USA.
Exp Physiol. 2009 Aug;94(8):928-36. doi: 10.1113/expphysiol.2009.047712. Epub 2009 May 8.
Protease-activated receptor 2 (PAR(2)) is involved in airway inflammation and airway hyperresponsiveness; both are the prominent features of asthma. Transient receptor potential vanilloid receptor 1 (TRPV1) is expressed in pulmonary sensory nerves, functions as a thermal and chemical transducer and contributes to neurogenic inflammation. Using cell-attached single-channel recordings we investigated the effect of PAR(2) activation on single TRPV1channel activities in isolated pulmonary sensory neurons. Our immunohistochemical study demonstrated the expression of PAR(2) in rat vagal pulmonary sensory neurons. Our patch clamp study further showed that intracellular application of capsaicin (0.75 microM) induced single channel current that exhibited outward rectification in these neurons. The probability of the channel being open (Po) was significantly increased after the cells were pretreated with PAR2-activating peptide (100 microM, 2 min). Pretreatment with trypsin (0.1 microM, 2 min) also increased the single-channel Po, and the effect was completely inhibited by soybean trypsin inhibitor (0.5 microM, 3 min). In addition, the effect of PAR2 activation was abolished by either U73122 (1 microM, 4 min),a phospholipase C inhibitor, or chelerythrine (10 microM, 4 min), a protein kinase C inhibitor. In conclusion, our data demonstrated that activation of PAR2 upregulated single-channel activitiesofTRPV1and that the effect was mediated through the protein kinase C-dependent transduction pathway.
蛋白酶激活受体2（PAR(2)）参与气道炎症和气道高反应性；这两者都是哮喘的突出特征。瞬时受体电位香草酸受体1（TRPV1）在肺感觉神经中表达，作为一种热和化学传感器发挥作用，并促成神经源性炎症。我们使用细胞贴附式单通道记录法，研究了PAR(2)激活对分离的肺感觉神经元中单个TRPV1通道活性的影响。我们的免疫组织化学研究证明了PAR(2)在大鼠迷走神经肺感觉神经元中的表达。我们的膜片钳研究进一步表明，在这些神经元中，细胞内应用辣椒素（0.75微摩尔）可诱导单通道电流，该电流表现出外向整流。在用PAR2激活肽（100微摩尔，2分钟）预处理细胞后，通道开放概率（Po）显著增加。用胰蛋白酶（0.1微摩尔，2分钟）预处理也增加了单通道Po，且该效应被大豆胰蛋白酶抑制剂（0.5微摩尔，3分钟）完全抑制。此外，PAR2激活的效应被磷脂酶C抑制剂U73122（1微摩尔，4分钟）或蛋白激酶C抑制剂白屈菜红碱（10微摩尔，4分钟）消除。总之，我们的数据表明PAR2的激活上调了TRPV1的单通道活性，且该效应是通过蛋白激酶C依赖的转导途径介导的。
