Quantitation of toxin A-induced SP release and its inhibition by sulfasalazine and 5-ASA but not by sulfapyridine. The percentage of NK-1R-ir neuronal cell bodies in the myenteric plexus of the colon with >10 NK-1R-ir endosomes was determined in 20 cells per animal for each treatment as an index of endogenous SP release. Toxin A stimulated SP release and this effect was significantly inhibited by sulfasalazine and 5-ASA but not sulfapyridine. * versus no treatment; ** versus no treatment; # versus toxin A alone treatment.
