Regulatory mechanisms of ion and water transport across the eel intestine

离子和水穿过鳗鱼肠道运输的调节机制

基本信息

批准号：
02804062
负责人：
ANDO Masaki
金额：
$ 0.96万
依托单位：
Hiroshima University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

The NaCl and water absorption across the eel intestine was inhibited by serotonine (5-HT), acetylcholine (ACh) or atrial natriuretic peptide (ANP), ANP being the most potent inhibitor. The effects of ANP were completely abolished after pretreatment with 8BrcGMP, indicating that ANP acts through cGMP synthesis. Similarly, 5-HT seems to activate cAMP synthesis, since the inhibitory effects of 5-HT were significantly reduced after pretreatment with 8BrcAMP. ACh seems to enhance the intracellular Ca^<2+> concentration, however the effect of Ca^<2+> ionophore, ionom-ycin, was not sufficient to mimic the effect of ACh, suggesting involvement of other mediators.When the intestine was stimulated electnically, the Cl^- transport was reduced transiently. The transient response was inhibited by 70% with atropine, a muscarinic ACh antagonist, and ICS-205930, a 5-HT antagonist, indicating that 70% of the effect of field-stimulation is due to release of ACh and 5HT. The remainig 30% must-be due to other regulators.On the other hand, adrenaline (AD) enhanced the NaCl and water absorption after pretreatment with 5-HT and ACh. The effects of AD were completely abolished with yohimbine, alpha_2-receptor antagonist. Moreover, the effects of AD were still observed even in the presence of 8BrCAMP and ionomyein, suggesting that AD acts on a post-cAMP and post-Ca^<2+> process.A novel peptide was also extracted from the eel intestine, but had no effect on the ion and water transport. The eel intestinal pentapeptide (EIPP, H-Gly-Phe-Trp-Asn-Lys-OH) enhanced the contraction of the srnooth muscle in the digestive tract such as esophagus, stomach and intestine.

鳗鱼肠道内的 NaCl 和水吸收受到血清素 (5-HT)、乙酰胆碱 (ACh) 或心房钠尿肽 (ANP) 的抑制，ANP 是最有效的抑制剂。用8BrcGMP预处理后，ANP的作用完全消失，表明ANP是通过cGMP合成发挥作用的。同样，5-HT 似乎可以激活 cAMP 合成，因为用 8BrcAMP 预处理后 5-HT 的抑制作用显着降低。 ACh 似乎可以增强细胞内 Ca^2+ 浓度，但是 Ca^2+ 离子载体离子霉素的作用不足以模拟 ACh 的作用，表明其他介质的参与。在电刺激下，Cl^-传输暂时减少。阿托品（一种毒蕈碱 ACh 拮抗剂）和 ICS-205930（一种 5-HT 拮抗剂）可将瞬时反应抑制 70%，表明 70% 的场刺激效应是由于 ACh 和 5HT 的释放。剩余的30%必须是由于其他调节剂。另一方面，用5-HT和ACh预处理后，肾上腺素(AD)增强了NaCl和水的吸收。 AD 的影响被α_2 受体拮抗剂育亨宾完全消除。此外，即使在8BrCAMP和ionomyein存在的情况下，仍然观察到AD的作用，这表明AD作用于cAMP后和Ca^2+后过程。还从鳗鱼肠中提取了一种新的肽，但对离子和水的传输没有影响。鳗鱼肠五肽（EIPP，H-Gly-Phe-Trp-Asn-Lys-OH）增强食道、胃、肠等消化道平滑肌的收缩。