Noxious heating of the skin releases immunoreactive substance P in the substantia gelatinosa of the cat: a study with antibody microprobes.

Using a new method, the antibody microprobe technique, the release of immunoreactive substance P (SPiR) in the dorsal horn in response to noxious heating of the skin, was studied in barbiturate anaesthetized spinal cats. Release of SPiR was not produced by immersing the ipsilateral hind paw in water at 37 degrees C. With water at 50 and 52 degrees C, however release was consistently detected in the region of the substantia gelatinosa. These results directly show a central release of SPiR with excitation of nociceptors by heat.