Capsaicin activates neurogenic non-adrenergic non-cholinergic relaxations of the isolated rat duodenum.

Capsaicin induces a transient relaxation of the isolated rat duodenum in the presence of atropine plus guanethidine. The relaxant effect of capsaicin was not observed in vitro in the duodenum of capsaicin-pretreated animals. Capsaicin-induced relaxation was antagonized by tetrodotoxin or cold storage (24 h at 4 degrees C). It is concluded that capsaicin produces a neurogenic relaxation of the rat duodenum by activating an intramural non-adrenergic non-cholinergic mechanism which inhibits intestinal motility.