Effect of capsaicin on release of substance P-like immunoreactivity from vascularly perfused rat duodenum.

The release of substance P-like immunoreactivity (SPLI) from the rat duodenum was investigated using an in situ vascularly perfused preparation. Results show that the basal release of SPLI was measurable and significantly enhanced by the administration of both 1,3, and 10 microM of capsaicin, indicating that SPLI is present in capsaicin-sensitive afferent nerve fibers. It is concluded that the present model may be useful for the study of the control of duodenal release of SPLI.