text: The potency of the antipsychotic drug, << risperidone >>, to antagonize alpha 1A-adrenoceptor-mediated contraction in rat vas deferens and vasoconstriction in rat perfused kidney, and [[ alpha 1B-adrenoceptor ]]-mediated contractions in spleen from guinea-pig and mouse was evaluated and compared to that of alpha 1-adrenoceptor subtype-discriminating antagonists.