title: H1- and H2-receptors for histamine in the ileum of the guinea pig.
abstract: Clark's equation used in its inverted form (double reciprocal plots) was shown to be valid regarding the interaction of histamine with its receptors in the guinea-pig ileum. Burimamide, a typical H2-receptor antagonist potentiated the stimulating effect of small concentrations of histamine (10(-6) M) on the intestinal smooth muscle, probably, by blocking H2-receptors which may show the opposite effect. The calculated parameters of affinity (pKn) remained constant under different conditions. A linear correlation between length of the preparation and maximal contractions has been found.
mesh_terms: D000818:Animals; D002049:Burimamide / Q000494:pharmacology; D055598:Chemical Phenomena; D002621:Chemistry; D004357:Drug Synergism; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects*; D066298:In Vitro Techniques; D007700:Kinetics; D009119:Muscle Contraction / Q000187:drug effects*; D011968:Receptors, Histamine / Q000187:drug effects*; D011969:Receptors, Histamine H1 / Q000187:drug effects*; D011970:Receptors, Histamine H2 / Q000187:drug effects*
chemical_list: D011968:Receptors, Histamine; D011969:Receptors, Histamine H1; D011970:Receptors, Histamine H2; D002049:Burimamide