Suppressive effect of ciramadol on the bradykinin-induced activities of the lamina V-type cells of the rat spinal dorsal horn.

The effects of a new analgesic drug, ciramadol, on single neuronal activities of lamina V-type cells of the spinal dorsal horn were investigated in spinal rats when applied microelectrophoretically to the cells or administered systemically. In the majority of lamina V-type cells examined, ciramadol inhibited the activities induced by intra-arterial injection of bradykinin (painful stimulation) but not those induced by mechanical noxious and innocuous stimuli. These results directly evidence that ciramadol acts on the lamina V-type cells of the spinal dorsal horn to block the bradykinin-induced (nociceptive) activities there.