Department of Biological Sciences, Bethel University, St. Paul, MN 55112, USA.
Poult Sci. 2013 Aug;92(8):2156-62. doi: 10.3382/ps.2013-03079.
The contractile effects of neurotensin (NT) and cholecystokinin octapeptide (CCK-8) on isolated circular smooth muscle strips of chicken gallbladder were investigated. The NT (0.25-300 nM) produced concentration-dependent contractions on smooth muscle with an EC50 of 8.5 nM (95% confidence limits = 5.3-13.6 nM). In comparison, CCK-8 produced concentration-dependent contractions with an EC50 of 13 nM (95% confidence limits of 9-20 nM). There were no statistical differences in contractile responses when comparing NT and CCK-8 at equimolar concentrations. The NT appears to act directly on smooth muscle tissue in the chicken; the contractile responses were not blocked by 10 µM atropine or tetrodotoxin. A portion of the activity is mediated by extracellular calcium as 100 nM nifedipine inhibited 30% of peptide-induced muscle tension. The NT receptor (NTR) type 1 antagonist SR 48692 (0.1 µM) did not significantly reduce NT potency. The contractile effects of CCK-8 remained unaltered in tissues pretreated with atropine, TTX, or nifedipine. The CCK-A antagonist lorglumide, at a concentration of 1 µM, reduced the contractile potency of CCK-8 by one-half. Avian receptors for NT and CCK may differ pharmacologically from their mammalian counterparts, but their contractile actions on the gallbladder resulting in increased biliary output by flow are further evidence of their role in the postprandial regulation of lipid digestion in chickens.
研究了神经降压素（NT）和胆囊收缩素八肽（CCK-8）对鸡胆囊分离环形平滑肌条的收缩作用。NT（0.25-300 nM）对平滑肌产生浓度依赖性收缩，EC50 为 8.5 nM（95%置信区间= 5.3-13.6 nM）。相比之下，CCK-8 产生浓度依赖性收缩，EC50 为 13 nM（95%置信区间为 9-20 nM）。当比较等摩尔浓度的 NT 和 CCK-8 时，收缩反应没有统计学差异。NT 似乎直接作用于鸡的平滑肌组织；10 µM 阿托品或河豚毒素不能阻断收缩反应。部分活性由细胞外钙介导，因为 100 nM 硝苯地平抑制肽诱导的肌肉张力的 30%。NT 受体（NTR）1 型拮抗剂 SR 48692（0.1 µM）并未显著降低 NT 的效力。CCK-8 的收缩作用在预先用阿托品、TTX 或硝苯地平处理的组织中保持不变。CCK-A 拮抗剂 lorglumide（1 µM）使 CCK-8 的收缩效力降低一半。禽类 NT 和 CCK 的受体在药理学上可能与哺乳动物的受体不同，但它们对胆囊的收缩作用导致胆汁流量增加，进一步证明了它们在鸡餐后脂质消化调节中的作用。
