Arima T, Mizuno T, Ohshima Y, Kitamura Y, Segawa T, Nomura Y
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan.
Neurosci Res. 1997 Mar;27(3):229-33. doi: 10.1016/s0168-0102(97)01156-5.
A novel pathway of 5-hydroxytryptamine (5-HT)-induced cGMP formation, which does not require Ca2+ and is distinct from the 5-HT, receptor-mediated pathway, is reported to exist in NG108-15 cells. Although the possible involvement of undefined 5-HT receptors and membrane-bound guanylyl cyclase is suggested. the mechanism is not clarified in detail in this Ca2+ -independent cGMP formation. In the present study, we investigated the activation mechanism of guanylyl cyclase activity. 5-HT-induced Ca2+ -independent cGMP formation was not observed in the cell membrane preparation. In intact cells, the 5-HT-induced Ca2+ -independent cGMP formation was inhibited by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazolin-1-oxyl 3-oxide (carboxyPTIO), a nitric oxide (NO)-specific trapper, and by 3,7-bis(dimethylamino)-phenothiazinium chloride (methylene blue), a cytosolic guanylyl cyclase-specific inhibitor, suggesting the involvement of NO and cytosolic guanylyl cyclase. Ca2+ -independent cGMP formation was not inhibited by 1,2-bis(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid tetra(acetoxymethyl)ester (BAPTA-AM), N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), and various arginine-derivative nitric oxide synthase (NOS) inhibitors. Our findings suggest that 5-HT stimulation results in the generation of NO followed by cGMP formation in an NOS-independent manner in NG108-15 cells.
据报道，在NG108 - 15细胞中存在一种新型的5 - 羟色胺（5 - HT）诱导的环磷酸鸟苷（cGMP）形成途径，该途径不需要Ca2 + ，且与5 - HT受体介导的途径不同。尽管提示可能涉及未明确的5 - HT受体和膜结合鸟苷酸环化酶，但在这种不依赖Ca2 + 的cGMP形成过程中，其机制尚未得到详细阐明。在本研究中，我们研究了鸟苷酸环化酶活性的激活机制。在细胞膜制剂中未观察到5 - HT诱导的不依赖Ca2 + 的cGMP形成。在完整细胞中，5 - HT诱导的不依赖Ca2 + 的cGMP形成受到2 -（4 - 羧基苯基）- 4,4,5,5 - 四甲基咪唑啉 - 1 - 氧基3 - 氧化物（羧基PTIO，一种一氧化氮（NO）特异性捕获剂）和3,7 - 双（二甲基氨基）- 吩噻嗪氯化铵（亚甲蓝，一种胞质鸟苷酸环化酶特异性抑制剂）的抑制，提示NO和胞质鸟苷酸环化酶的参与。不依赖Ca2 + 的cGMP形成不受1,2 - 双（邻氨基苯氧基）乙烷 - N，N，N'，N' - 四乙酸四（乙酰氧甲基）酯（BAPTA - AM）、N -（6 - 氨基己基）- 5 - 氯 - 1 - 萘磺酰胺（W - 7）以及各种精氨酸衍生的一氧化氮合酶（NOS）抑制剂的抑制。我们的研究结果表明，在NG108 - 15细胞中，5 - HT刺激导致以不依赖NOS的方式产生NO，随后形成cGMP。
