Maki Tomoko, Kajioka Shunichi, Itsumi Momoe, Kareman Eljamal, Lee Ken, Shiota Masaki, Eto Masatoshi
Department of Urology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Department of Clinical Pharmacology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Low Urin Tract Symptoms. 2019 Apr;11(2):O209-O217. doi: 10.1111/luts.12247. Epub 2019 Jan 10.
We previously found that mirabegron exerts a relaxant effect in the presence of the β -adrenoceptor antagonist SR58894A during carbachol-induced contraction in human and pig detrusor. The aim of this study was to explore the possible mechanism underlying the relaxant effects of mirabegron using detrusor smooth muscle.
Human tissue was obtained from urinary bladders of patients undergoing radical cystectomy at Kyushu University and Harasanshin Hospital. Pig tissue was obtained from an abattoir. Tension force (organ bath experiments) was measured in intact or permeabilised (α-toxin or β-escin) detrusor smooth muscle strips. The contribution of cAMP-dependent signaling and the inhibition of Ca sensitization to the relaxant effects of mirabegron were characterized using 1 μM SR58894A, 100 μM SQ22536 (an adenylyl cyclase inhibitor), 10 μM H-89 (a protein kinase [PK] A inhibitor), 10 μM Y-27632 (a selective Rho kinase inhibitor), and 10 μM GF-109203X (a selective PKC inhibitor).
30 μM Mirabegron impaired carbachol (0.03-1 μM)-induced contraction in human detrusor smooth muscle. SR58894A only partially attenuated the relaxant effects of mirabegron in human and pig detrusor strips precontracted with 1 μM carbachol. In α-toxin-permeabilized detrusor strips, tension force at 1 μM [Ca ] was decreased by mirabegron in a concentration-dependent manner. The relaxant effect of mirabegron was only slightly attenuated by H-89 and not significantly affected by SQ22536. Y-27632 potentiated the relaxation response to mirabegron, but attenuated responses to cAMP; GF-109203X had little effect. Mirabegron but not cAMP had a notable relaxant effect in the pig detrusor smooth muscle permeabilized with β-escin.
Mirabegron-induced relaxation of pig and human detrusor smooth muscle occurs via both a β -adrenoceptor/cAMP-dependent and -independent pathway.
我们之前发现，在卡巴胆碱诱导人及猪逼尿肌收缩过程中，米拉贝隆在β肾上腺素受体拮抗剂SR58894A存在的情况下发挥舒张作用。本研究旨在利用逼尿肌平滑肌探索米拉贝隆舒张作用的潜在机制。
人组织取自九州大学和原山新医院接受根治性膀胱切除术患者的膀胱。猪组织取自屠宰场。在完整或经通透处理（α毒素或β七叶皂苷）的逼尿肌平滑肌条上测量张力（器官浴实验）。使用1 μM SR58894A、100 μM SQ22536（一种腺苷酸环化酶抑制剂）、10 μM H-89（一种蛋白激酶[PK]A抑制剂）、10 μM Y-27632（一种选择性Rho激酶抑制剂）和10 μM GF-109203X（一种选择性蛋白激酶C抑制剂）来表征cAMP依赖性信号传导的作用以及对Ca敏化的抑制对米拉贝隆舒张作用的影响。
30 μM米拉贝隆减弱了卡巴胆碱（0.03 - 1 μM）诱导的人逼尿肌平滑肌收缩。SR58894A仅部分减弱了米拉贝隆对预先用1 μM卡巴胆碱预收缩的人及猪逼尿肌条的舒张作用。在α毒素通透处理的逼尿肌条中，米拉贝隆以浓度依赖性方式降低了1 μM [Ca] 时的张力。米拉贝隆的舒张作用仅被H-89轻微减弱，且未被SQ22536显著影响。Y-27632增强了对米拉贝隆的舒张反应，但减弱了对cAMP的反应；GF-109203X几乎没有作用。米拉贝隆而非cAMP对用β七叶皂苷通透处理的猪逼尿肌平滑肌有显著的舒张作用。
米拉贝隆诱导的猪和人逼尿肌平滑肌舒张通过β肾上腺素受体/cAMP依赖性和非依赖性途径发生。
