The interaction of 1-(2(diarylmethoxy)ethyl)aziridines with histamine receptors in the longitudinal muscle strip of the guinea pig ileum.

The time course of the onset and decline of histamine antagonism by 1-(2-(diarylmethoxy)ethyl)aziridines, compounds which could be expected to have H1-receptor alkylating properties, was investigated on the longitudinal muscle strip of the guinea pig ileum. Experiments were performed with normal preparations and with muscle strips pretreated with a prostaglandin synthesis inhibitor in order to prevent spontaneous rise of muscle tone. In contrast to the previously reported observation that antihistaminic potency decreased with prolongation of the preincubation time, histamine antagonism by the aziridine compounds remained at a constant level for more than 60 min in the presence of indomethacin. This indicated that the aziridines are not hydrolyzed either directly in solution or after interaction with the tissue since the supposed hydrolysis product had a significantly lower antihistaminic activity. A comparison between 1-(2-diphenylmethoxy)ethyl)aziridine and diphenhydramine showed the former compound to have a slightly more rapid onset and a considerably more rapid decline of histamine receptor blockade. It was concluded that 1-(2-(diarylmethoxy)ethyl)aziridines did not alkylate the histamine H1-receptor in the longitudinal muscle layer of the guinea pig ileum.