[The effect of histamine and histamine H1 and H2 receptor blockers on the tone of the longitudinal muscles in the human appendix].

The aims of this study were to determine whether the effect of histamine on a smooth musculature of the human appendix is mediated by histamine H1-receptors only or whether histamine H2-receptors are involved, as well. The obtained results indicate histamine increases tonus in musculature; however, histamine H1-receptor antagonist (promethazine) decreases tonus. Histamine H2-receptor antagonist (cimetidine) has caused a mild increase in tonus of musculature what indicates that it has a certain intrinsic activity. By blocking histamine receptors with H1 and H2 antagonists which were used either separately or together before cumulative histamine concentrations, it has been concluded that histamine actions are exerted not exclusively by H1-receptors but also histamine H2-receptor antagonists can significantly decrease the tonicizing effect of histamine.