Bientinesi Riccardo, Mancuso Cesare, Martire Maria, Bassi Pier Francesco, Sacco Emilio, Currò Diego
Department of Surgical Sciences, School of Medicine, Catholic University of the Sacred Heart, L.go F. Vito 1, 00168, Rome, Italy.
Institute of Pharmacology, School of Medicine, Catholic University of the Sacred Heart, L.go F. Vito 1, 00168, Rome, Italy.
Naunyn Schmiedebergs Arch Pharmacol. 2017 Feb;390(2):127-137. doi: 10.1007/s00210-016-1312-9. Epub 2016 Oct 19.
Voltage-gated type 7 K (K7 or KCNQ) channels regulate the contractility of various smooth muscles. With this study, we aimed to assess the role of K7 channels in the regulation of human detrusor contractility, as well as the gene and protein expression of K7 channels in this tissue. For these purposes, the isolated organ technique, RT-qPCR, and Western blot were used, respectively. XE-991, a selective K7 channel blocker, concentration-dependently contracted the human detrusor; mean EC and E of XE-991-induced concentration-response curve were 14.1 μM and 28.8 % of the maximal bethanechol-induced contraction, respectively. Flupirtine and retigabine, selective K7.2-7.5 channel activators, induced concentration-dependent relaxations of bethanechol-precontracted strips, with maximal relaxations of 51.6 and 51.8 % of the precontraction, respectively. XE-991 blocked the relaxations induced by flupirtine and retigabine. All five KCNQ genes were found to be expressed in the detrusor with KCNQ4 being the most expressed among them. Different bands, having sizes similar to some of reported K7.1, 7.4, and 7.5 channel subunit isoforms, were detected in the detrusor by Western blot with the K7.4 band being the most intense among them. In conclusion, K7 channels contribute to set the basal tone of the human detrusor. In addition, K7 channel activators significantly relax the detrusor. The K7.4 channels are probably the most important K7 channels expressed in the human detrusor. These data suggest that selective K7.4 channel activators might represent new pharmacological tools for inducing therapeutic relaxation of the detrusor.
电压门控型7钾通道（K7或KCNQ）调节各种平滑肌的收缩性。在本研究中，我们旨在评估K7通道在调节人逼尿肌收缩性中的作用，以及该组织中K7通道的基因和蛋白表达。为此，分别采用了离体器官技术、逆转录-定量聚合酶链反应（RT-qPCR）和蛋白质免疫印迹法。选择性K7通道阻滞剂XE-991能浓度依赖性地收缩人逼尿肌；XE-991诱导的浓度-反应曲线的平均半数有效浓度（EC）和最大效应（E）分别为14.1 μM和最大氨甲酰甲胆碱诱导收缩的28.8%。选择性K7.2-7.5通道激活剂氟吡汀和瑞替加滨能诱导氨甲酰甲胆碱预收缩条带浓度依赖性舒张，最大舒张分别为预收缩的51.6%和51.8%。XE-991能阻断氟吡汀和瑞替加滨诱导的舒张。发现所有5种KCNQ基因均在逼尿肌中表达，其中KCNQ4表达量最高。通过蛋白质免疫印迹法在逼尿肌中检测到大小与一些报道的K7.1、7.4和7.5通道亚基异构体相似的不同条带，其中K7.4条带最明显。总之，K7通道有助于设定人逼尿肌的基础张力。此外，K7通道激活剂能显著舒张逼尿肌。K7.4通道可能是人逼尿肌中表达的最重要的K7通道。这些数据表明，选择性K7.4通道激活剂可能代表诱导逼尿肌治疗性舒张的新型药理学工具。
