4-P-Aminoethylpyrazole (11) also stimulates gastric acid secretion but to a lesser degree than I. It is about one-half as active as I in this respect. 3b The hypothesis has been advanced that one of the minimum requirements for histaminelike activity of an organic compound is the presence of the structure I11 or IV within the moleculeba This hypothesis must now be modified, since I1 does not contain either of these structures.
![[2-(1H-吡唑-4-基)乙基]胺结构式](https://image.chemsrc.com/caspic/391/42150-24-3.png)