Nitric oxide release from substantia gelatinosa of the rat spinal cord in vitro

To study characteristics of nitric oxide (NO) release from substantia gelat inosa (SG) in the spinal cord, we measured NO concentration in transverse s pinal cord slices of rats using electrochemical NO probes. Electrical stimu lation of the dorsomedial white matter adjacent to SG elicited transient cu rrent changes in NO probes placed on SG and the amplitude corresponded to a NO concentration of 200-300 pM. This NO release was not affected by the ap plication of antagonists of glutamate or substance P receptors. The NO rele ase in the rats, which were neonatally treated with capsaicin for denervati ng C-fibers, was significantly smaller than that in control rats. These dat a suggest that NO is mainly derived from the unmyelinated afferent nerves i n the SG of the spinal cord. (C) 1999 Elsevier Science Ireland Ltd. All rig hts reserved.