2,3-Dibenzylbutane-1,4-diol (DBB) is a mammalian lignan derived from human urine. To investigate the pharmacological actions of mammalian lignans, the effects of DBB on high K(+)-induced contraction in rabbit femoral artery were studied. High K+ induced a transient contraction followed by sustained contraction, and both depended on extracellular Ca2+. DBB inhibited transient contraction as well as sustained contraction. Verapamil or nifedipine inhibited sustained contraction more effectively than transient contraction. DBB inhibited the transient contraction remaining in the verapamil- or the nifedipine-pretreated preparation in a concentration-dependent manner. Moreover, DBB inhibited sustained contraction elicited by Bay K 8644 (Ca2+ channel activator). These results indicate that DBB effects not only the sensitive Ca2+ channels but also the insensitive channels.