Studies on the mode of antagonism between adrenergic beta-mimetics and beta-blocking agents (III). Functional antagonism between beta-mimetics and spasmogens.
New equations which can explain the following characteristic phenomena in the functional antagonism between isoproterenol (ISO) and spasmogens in guinea-pig trachea are proposed: (1) The amplitude of relaxation of the muscle induced by ISO varied depending on the concentration of a spasmogen used (histamine or carbachol). (2) The dose-response curves for the relaxation by ISO shifted to the right in a parallel manner as the concentration of the spasmogen increased, and became stationary at high concentrations of the spasmogen. (3) The slope of the dose-response curve became steeper with increasing concentrations of the spasmogen. When the saturable uptake process of ISO was taken into consideration, a satisfactory parallel was seen between the theoretical dose-response curves and the present experimental results.
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D003983:Dibenzylchlorethamine / Q000494:pharmacology; D004347:Drug Interactions; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D007700:Kinetics; D009119:Muscle Contraction / Q000187:drug effects*; D014132:Trachea / Q000187:drug effects
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D003983:Dibenzylchlorethamine; D006632:Histamine; D002217:Carbachol