A series of derivatives of the biologically active C-terminus of gastrin was synthesized to study the structural activity of the molecule and also to determine the smallest and highest affinity inhibitor of gastrin. Earlier work speculated that a peptide resistant to dipeptidase contained in a receptor would be an effective gastrin antagonist. Methods: Five dogs with both chronic gastric fistulae and Heidenhein pouches were used. After an 18 hour fast, gastric juice was collected both from the gastric fistula and pouch over 200 minutes at 10 minute intervals. MMC (Migrating Motor Complex) was monitored by a small balloon in the gastric antrum. Collections were initiated at the beginning of phase I of the MMC and were obtained under 3 conditions: Control, pentagastrin infusion (0.5 .mu.g/Kg/h, i.v.) and pentagastrin+peptide infusion (Indole propionic acid [IPA]- Leu-Asp-Phenethyl amine [PEA], Boc-Trp-Leu-.beta.Ala, IPA-Leu-.beta.Ala, or Boc-Trp-Leu-Asp-methyl meta Aminobenzoic acid mABAOMe] at 20 pmol/kg/h for 70 min.). Pentagastrin infusion was started immediately before the next peak of the MMC. Peptides were infused 60 minutes after starting pentagastrin infusion. Results: All four peptides inhibited the stimulated acid secretion causing it to approach the control level. ______________________________________ Inhibition of the stimulated acid secretion (.DELTA. meq/kg) Heidenhein Gastric Fistula Pouch ______________________________________ IPA--Leu--Asp--PEA .dwnarw.303 .+-. 120* .dwnarw.18 .+-. 11* Boc--Trp--Leu-.beta.Ala .dwnarw.618 .+-. 168** .dwnarw.35 .+-. 8** IPA--Leu-.beta.Ala .dwnarw.562 .+-. 249* .dwnarw.34 .+-. 12* Boc--Trp--Leu--Asp- .dwnarw.446 .+-. 172** .dwnarw.40 .+-. 16** mABAOMe ______________________________________ (*p < 0.05 **p < 0.01, mean .+-. s.e.) PAL It is concluded that even small di-and tripeptide derivatives of the gastrin C-terminal fragment with varied resistance to hydrolysis can exhibit antagonist activity to pentagastrin stimulated gastric acid secretion.
为了研究胃泌素分子的结构活性并确定最小和最高亲和力的胃泌素
抑制剂,合成了一系列具有
生物活性的胃泌素C-末端衍
生物。先前的研究推测,对受体中存在的
二肽酶抵抗性肽肽可能是有效的胃泌素拮抗剂。方法:使用了五只同时患有慢性胃瘘和海登海因囊的狗。在18小时禁食后,以10分钟间隔在200分钟内从胃瘘和囊中收集胃液。通过胃窦中的小气球监测MMC(迁移性运动复合物)。收集是在MMC的第一阶段开始时启动的,并在三种情况下进行:对照组、
五肽胃泌素注射(0.5μg / Kg / h,i.v.)和
五肽胃泌素+肽注射(
吲哚丙酸[IPA]-亮-
天冬氨酸-苯
乙胺[
PEA],Boc-色
氨酸-亮-
β-丙氨酸,IPA-亮-
β-丙氨酸或Boc-色
氨酸-亮-
天冬氨酸-甲基
间氨基苯甲酸mABAOMe],每小时20 pmol / kg,持续70分钟)。
五肽胃泌素注射是在MMC的下一个峰值前立即开始的。肽注射是在开始
五肽胃泌素注射后60分钟进行的。结果:所有四个肽都抑制了刺激酸分泌,使其接近对照
水平。______________________________________刺激酸分泌的抑制(Δmeq / kg)海登海因胃瘘囊________________________________________
吲哚丙酸-亮-
天冬氨酸-苯
乙胺.dwnarw.303 .+-. 120 * .dwnarw.18 .+-. 11 *Boc-色
氨酸-亮-
β-丙氨酸.dwnarw.618 .+-. 168 ** .dwnarw.35 .+-. 8 **IPA-亮-
β-丙氨酸.dwnarw.562 .+-. 249 * .dwnarw.34 .+-. 12 *Boc-色
氨酸-亮-
天冬氨酸-甲基
间氨基苯甲酸.dwnarw.446 .+-. 172 ** .dwnarw.40 .+-. 16 **mABAOMe______________________________________(*p<0.05 **p<0.01,平均值.+-. s.e.)PAL得出结论,即即使是胃泌素C末端片段的小二肽和三肽衍
生物,具有不同的
水解抵抗性,也可以表现出对
五肽胃泌素刺激的胃酸分泌的拮抗作用。