Intracolonic Release of Nitric Oxide During Trinitrobenzene Sulfonic Acid Rat Colitis

Nitric oxide is thought to play an importantrole in modulating the inflammatory process. Recently anincrease in the inducible form of nitric oxide synthase(iNOS) has been found in the rat trinitrobenzene sulfonic acid model of experimental colitis,and inhibition of nitric oxide synthase activityresulted in an amelioration of tissue injury. The aim ofour study was to evaluate in vivo intracolonic release of nitric oxide in this model of colitis.Experimental colitis was induced in male Sprague-Dawleyrats by a single intracolonic administration oftrinitrobenzene sulfonic acid. Nitrite levels weredetermined in rectal dialysates by HPLC. The tissuemyeloperoxidase and iNOS and the luminal leukotrieneB 4 were also measured. Nitrite levels weresignificantly increased in rectal dialysates duringcolitis and correlated significantly with tissue myeloperoxidase andiNOS activity. The correlation between nitrite dialysatelevels and wall iNOS activity confirms that nitrite indialysates is produced by inflammatory cells and not by colonic bacterial flora.Determination of nitrite levels in rectal dialysatesseems a valuable method to monitor colonic inflammationin rat trinitrobenzene sulfonic acid colitis.