Tanaka Yoshimasa, Ihara Eikichi, Hirano Katsuya, Takahashi Shunsuke, Hirano Mayumi, Nakamura Kazuhiko, Akiho Hirotada, Oda Yoshinao, Takayanagi Ryoichi
Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Eur J Pharmacol. 2015 Apr 5;752:97-105. doi: 10.1016/j.ejphar.2015.02.008. Epub 2015 Feb 18.
The lower esophageal sphincter (LES) plays an important role in coordinated esophageal motility. The present study aimed to elucidate how trypsin affects LES contractility. Porcine LES circular smooth muscle strips were prepared. Contractile responses to trypsin were assessed. Trypsin (300nM) induced a transient contraction. At concentrations of 1μM or higher, trypsin induced biphasic responses, consisting of a transient contraction followed by a transient relaxation. Pretreatment with either 1μM tetrodotoxin or carbenoxolone had no effect on these responses. In contrast, trypsin-induced responses were completely blocked by pretreatment with the serine protease inhibitor. Pretreatment with 10μM FSLLRY-NH2, a PAR2 antagonist, significantly inhibited trypsin-induced biphasic responses. Trypsin (1μM)-induced contractions were partially inhibited by pretreatment with 10μM Y-27632. In addition, trypsin (10μM)-induced relaxation was partially inhibited by pretreatment with 10μM Y-27632, 10μM PD98059 or 10μM SB203580. Trypsin-induced relaxation was abolished by increasing the extracellular K(+) concentration to 40mM, but not by pretreatment with l-arginine methyl ester. Furthermore, trypsin-induced relaxation was partially inhibited by pretreatment with 10μM glibenclamide or 1μM 4-aminopyridine. Trypsin causes biphasic regulation of LES tone by directly acting on smooth muscle. Rho-associated protein kinase (ROK) is involved in trypsin-induced contraction, whereas ROK, ERK1/2, p38MAPK, and membrane hyperpolarization are involved in relaxation. The regulation of LES tone by trypsin may play a role in esophageal motility.
食管下括约肌（LES）在协调食管动力方面发挥着重要作用。本研究旨在阐明胰蛋白酶如何影响LES的收缩性。制备了猪LES环形平滑肌条。评估了对胰蛋白酶的收缩反应。胰蛋白酶（300nM）诱导了短暂收缩。在浓度为1μM或更高时，胰蛋白酶诱导双相反应，包括短暂收缩后接着短暂舒张。用1μM河豚毒素或生胃酮预处理对这些反应没有影响。相反，胰蛋白酶诱导的反应被丝氨酸蛋白酶抑制剂预处理完全阻断。用10μM PAR2拮抗剂FSLLRY-NH2预处理可显著抑制胰蛋白酶诱导的双相反应。用10μM Y-27632预处理可部分抑制胰蛋白酶（1μM）诱导的收缩。此外，用10μM Y-27632、10μM PD98059或10μM SB203580预处理可部分抑制胰蛋白酶（10μM）诱导的舒张。将细胞外K⁺浓度增加到40mM可消除胰蛋白酶诱导的舒张，但用L-精氨酸甲酯预处理则不能。此外，用10μM格列本脲或1μM 4-氨基吡啶预处理可部分抑制胰蛋白酶诱导的舒张。胰蛋白酶通过直接作用于平滑肌对LES张力进行双相调节。Rho相关蛋白激酶（ROK）参与胰蛋白酶诱导的收缩，而ROK、ERK1/2、p38MAPK和膜超极化参与舒张。胰蛋白酶对LES张力的调节可能在食管动力中起作用。
