In an in vitro preparation of the neonatal rat spinal cord with attached tail, administration of bradykinin (Bk) to the spinal cord or to the tail produced depolarization of a ventral root (L3-L5). The effect of Bk at each site was selectively and reversibly antagonized by D-Arg [Hyp2, Thi5,8 D-Phe7]-Bk but could not be mimicked or antagonized by the B1-receptor ligands [des-Arg9]-Bk or Leu8[des-Arg9]-Bk, respectively. Peripherally evoked noxious responses produced by capsaicin or heat, were unaffected by either antagonist administered to the spinal cord. These data suggest that Bk-evoked responses in the spinal cord and at peripheral nociceptors were mediated via a receptor which by definition is of the B2-type. Additionally Bk is unlikely to be a physiological mediator of acute nociception in the spinal cord.