Persistence of immunoreactive neurokinins in the dorsal horn of barbiturate anaesthetized and spinal cats, following release by tibial nerve stimulation.

Antibody-coated microprobes were used to study the time course of release and disappearance of immunoreactive neurokinins in the dorsal spinal cord, in response to electrical stimulation of unmyelinated fibres of the tibial nerve of the cat. Noxious cutaneous stimuli were not used thereby avoiding potentially uncontrolled tissue damage and inflammation. Microprobes, inserted into the spinal cords of barbiturated anaesthetized spinal cats prior to nerve stimulation, detected a basal level of immunoreactive neurokinins. During nerve stimulation immunoreactive neurokinins were released significantly in the upper dorsal horn and dorsal columns and required at least 1 h to return to prestimulus levels. The persistence of immunoreactive neurokinins in the dorsal horn may underlie the prolonged hyperexcitability of some spinal neurons following brief noxious stimuli.