Kline L W, Zhang M L, Pang P K
Department of Oral Health Sciences, University of Alberta, Edmunton, Alberta, Canada T6G 2N8.
J Exp Biol. 1997 Oct;200(Pt 20):2669-74. doi: 10.1242/jeb.200.20.2669.
Cholecystokinin octapeptide (CCK), acetylcholine (ACh) and ceruletide have been shown to produce contraction in bullfrog (Rana catesbeiana) gallbladder strips. Agents capable of relaxing the bullfrog gallbladder are less numerous. Calcitonin gene-related peptide reduced the amount of both CCK- and ACh-induced tension in bullfrog gallbladder strips. The purpose of this study was to determine whether vasoactive intestinal peptide (VIP), nitric oxide (NO) and the second messengers cyclic GMP or cyclic AMP had any effect on gallbladder motility in the bullfrog. In vitro tension studies using l-NG-nitro-arginine methyl ester, Methylene Blue, sodium nitroprusside and N2,2'-O-dibutyryl guanosine 3',5'-cyclic monophosphate suggested that nitric oxide did not modulate gallbladder motility in the bullfrog gallbladder. Histochemical staining for NADPH diaphorase (nitric oxide synthase) failed to demonstrate nerve fibers containing nitric oxide synthase in the bullfrog gallbladder. In vitro studies demonstrated that VIP had no effect on CCK-induced tension. However, in vitro studies using either 8-bromoadenosine 3',5'-cyclic monophosphate or forskolin demonstrated that both agents relaxed strips precontracted with CCK. The results of this study suggested that, while neither NO nor VIP had a role in modulating bullfrog gallbladder motility, cyclic AMP was capable of modulating bullfrog gallbladder motility.
胆囊收缩素八肽（CCK）、乙酰胆碱（ACh）和蛙皮素已被证明可使牛蛙（Rana catesbeiana）胆囊条收缩。能够使牛蛙胆囊舒张的物质则较少。降钙素基因相关肽可降低CCK和ACh诱导的牛蛙胆囊条张力。本研究的目的是确定血管活性肠肽（VIP）、一氧化氮（NO）以及第二信使环磷酸鸟苷（cGMP）或环磷酸腺苷（cAMP）是否对牛蛙胆囊运动有任何影响。使用L-NG-硝基精氨酸甲酯、亚甲蓝、硝普钠和N2,2'-O-二丁酰环磷鸟苷进行的体外张力研究表明，一氧化氮不会调节牛蛙胆囊的运动。对NADPH黄递酶（一氧化氮合酶）的组织化学染色未能在牛蛙胆囊中显示出含有一氧化氮合酶的神经纤维。体外研究表明，VIP对CCK诱导的张力没有影响。然而，使用8-溴环磷酸腺苷或福斯可林进行的体外研究表明，这两种物质均可使预先用CCK预收缩的胆囊条舒张。本研究结果表明，虽然NO和VIP在调节牛蛙胆囊运动中均不起作用，但cAMP能够调节牛蛙胆囊运动。
