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组织胺协同剂使胃酸分泌增加。实现该作用其结构要求侧链需要有两个碳原子。若只有一个,则无协同效应,若增至三个,效应也很低,约为组织胺的千分之一;尾端的-NH_2也很重要。如以-OH取代,便失去药效。链加长,如加上一个一C_2H_5,仍有药效,但加上苯基(phellyl-),因几乎不能与受体适应而无效。碳末端的氢被甲基取代,效力比组织胺强2—3倍;两个氢被两个甲基取代后,在体内的效力也比组织胺强2—3倍。但组织胺在体外的直接作用比其甲基取代衍生物要强,而后者(N-甲基和N-双甲基组织胺)在体内比
Histamine synergists increase gastric acid secretion. Its structure requires that the side chain require two carbon atoms. If there is only one, there is no synergistic effect, if the increase to three, the effect is very low, about one thousandth of histamine; end of the -NH_2 is also important. If replaced by -OH, they lose their efficacy. Chain extension, such as adding a C_2H_5, there is still a pharmacodynamic effect, but with phenyl (phellyl-), because almost can not adapt to the receptor and invalid. Hydrogen at the carbon end is substituted by methyl, which is 2-3 times more potent than histamine; two hydrogens, which are substituted by two methyl groups, are 2-3 times more potent in vivo than histamine. However, the direct effect of histamine in vitro than its methyl-substituted derivatives is stronger, while the latter (N-methyl and N-dimethyl histamine) in vivo than