STUDIES ON THE MODE OF ANTAGONISM BETWEEN ADRENERGIC β-MIMETICS AND β-BLOCKING AGENTS (III) FUNCTIONAL ANTAGONISM BETWEEN β-MIMETICS AND SPASMOGENS

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Abstract
New equations which can explain the following characteristic phenomena in the functional antagonism between isoproterenol (ISO) and spasmogens in guinea-pig trachea are proposed: The amplitude of relaxation of the muscle induced by ISO varied depending on the concentration of a spasmogen used (histamine or carbachol). 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 higher concentrations of the spasmogen. 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.