Interaction of a beta-adrenergic partial agonist with its receptor in guinea-pig taenia caecum.

Beta-adrenoceptor mechanisms in guinea-pig taenia caecum were studied by means of a receptor-binding technique. Hill plots of test drugs obtained from inhibition curves were linear with slopes which were equal to 1.00. pKi-values of isoprenaline and desisopropylprocaterol were in agreement with those pD2-values. pKi-value of carteolol was in agreement with its pA2-value. The beta-adrenoceptor is suggested to have two different sites; one can interact with the agonist and partial agonist and the other can interact with the antagonist and partial agonist.