[Occurrence of atypical histamine H2 receptors in the wall of the frog subclavian vein].

Selective H2-histamine agonist dimaprit was shown to produce relaxation of the isolated frog subclavian vein, with it persisting under the effect of selective H2-histamine antagonist cimetidine. Possible nonspecific mechanisms of relaxation produced by histamine are discussed. The data presented do not exclude that there are atypical H2-histamine receptors in subclavian vein of frogs, the activation of which initiates the attenuation of the active tension.