[Relationships between structure and the noradrenaline depleting effects of guanidine and amidine derivatives (author's transl)].

In guinea pigs we studied the noradrenaline (NA) depletion in the sympathetic nerve terminals of the heart exerted by 24 derivatives of guanidine and amidine; the effects of these substances being considerably similar in their chemical structure were compared to those of reserpine, guanethidine, guanoxan and cyclazenin. Substitution of the free guanidine group to give an imidazoline or imidazolidine ring diminished the activity of the compounds. If the benzodioxane ring of guanoxan was "opened" to give a diether of catechol, the activity of the substances was not altered. We also observed a NA depletion after injection of some guanidine derivatives substituted with piperazine. The elongation of the aliphatic chain between guanidine and the aromatic substituent considerably decreased the activity of the compounds.