Crucial roles of nitric oxide synthases in β-adrenoceptor-mediated bladder relaxation in mice.
Crucial roles of nitric oxide synthases in β-adrenoceptor-mediated bladder relaxation in mice.
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DOI：
10.1152/ajprenal.00137.2016
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发表时间：
2016-03
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通讯作者：
Y. Satake;K. Satoh;Masamichi Nogi;J. Omura;Shigeo Godo;S. Miyata;Hiroki Saito;Shuhei Tanaka;Yosuke Ikumi;S. Yamashita;Y. Kaiho;M. Tsutsui;Y. Arai;H. Shimokawa
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作者：
Y. Satake;K. Satoh;Masamichi Nogi;J. Omura;Shigeo Godo;S. Miyata;Hiroki Saito;Shuhei Tanaka;Yosuke Ikumi;S. Yamashita;Y. Kaiho;M. Tsutsui;Y. Arai;H. Shimokawa
一氧化氮（NO）还原酶（NOS）在膀胱平滑肌中的具体作用尚不清楚。我们研究了NOS在β-肾上腺素受体（AR）介导的膀胱舒张中的作用。使用神经元NOS [nNOS敲除（KO）]、内皮NOS（eNOS-KO）、神经元/内皮NOS（n/eNOS-KO）、神经元/内皮/诱导型NOS（n/e/iNOS-KO）缺陷的雄性小鼠（C57 BL 6）及其对照[野生型（WT）]。在膀胱中进行免疫组织化学分析。然后，在用卡巴胆碱预收缩的膀胱条上检查对松弛剂的反应以及几种抑制剂对松弛反应的影响。免疫荧光染色显示nNOS和eNOS在膀胱尿道和平滑肌中表达。异丙肾上腺素诱导的舒张在nNOS-KO小鼠中显著降低，并且与WT小鼠相比，在n/eNOS-KO和n/e/iNOS-KO小鼠中进一步降低。在n/e/iNOS-KO小鼠中的松弛与在n/eNOS-KO小鼠中几乎相同。用Charybdotoxin和apamin抑制Ca 2+激活的K+（KCa）通道可消除WT小鼠中异丙肾上腺素诱导的膀胱舒张。此外，用NS 1619直接激活KCa通道在WT、nNOS-KO和n/eNOS-KO小鼠中引起相当程度的舒张。相反，NONOate（NO供体）或过氧化氢（H2 O2）（eNOS的另一种可能的舒张因子）引起最小的舒张，过氧化氢酶（H2 O2清除剂）对异丙肾上腺素诱导的舒张没有抑制作用。这些结果表明，nNOS和eNOS均通过激活KCa通道以NO或H2 O2非依赖性方式参与β-AR介导的膀胱舒张。
The specific roles of nitric oxide (NO) synthases (NOSs) in bladder smooth muscle remain to be elucidated. We examined the roles of NOSs in β-adrenoceptor (AR)-mediated bladder relaxation. Male mice (C57BL6) deficient of neuronal NOS [nNOS-knockout (KO)], endothelial NOS (eNOS-KO), neuronal/endothelial NOS (n/eNOS-KO), neuronal/endothelial/inducible NOS (n/e/iNOS-KO), and their controls [wild-type (WT)] were used. Immunohistochemical analysis was performed in the bladder. Then the responses to relaxing agents and the effects of several inhibitors on the relaxing responses were examined in bladder strips precontracted with carbachol. Immunofluorescence staining showed expressions of nNOS and eNOS in the urothelium and smooth muscle of the bladder. Isoproterenol-induced relaxations were significantly reduced in nNOS-KO mice and were further reduced in n/eNOS-KO and n/e/iNOS-KO mice compared with WT mice. The relaxation in n/e/iNOS-KO mice was almost the same as in n/eNOS-KO mice. Inhibition of Ca2+-activated K+ (KCa) channel with charybdotoxin and apamin abolished isoproterenol-induced bladder relaxation in WT mice. Moreover, direct activation of KCa channel with NS1619 caused comparable extent of relaxations among WT, nNOS-KO, and n/eNOS-KO mice. In contrast, NONOate (a NO donor) or hydrogen peroxide (H2O2) (another possible relaxing factor from eNOS) caused minimal relaxations, and catalase (H2O2 scavenger) had no inhibitory effects on isoproterenol-induced relaxations. These results indicate that both nNOS and eNOS are substantially involved in β-AR-mediated bladder relaxations in a NO- or H2O2-independent manner through activation of KCa channels.