HEMODYNAMICS IN THE COLONIC MUCOSA OF RATS WITH DEXTRAN SULFATE-INDUCED COLITIS IN THE EARLY PHASE

We investigated hemodynamics in the colonic mucosa of rats with experi mental colitis induced by the administration of dextran sulfate sodium (DSS). As parameters of hemodynamics, we determined the indices of mu cosal hemoglobin concentration (IHb) and mucosal oxygen saturation (IS O2), measured by reflectance spectrophotometry, and an index of coloni c mucosal blood flow (Flow), measured by laser-Doppler flowmetry. In t he ascending colon, each parameter was measured by a combination of th ese methods after 1, 3, 5, 7, and 10 days of DSS administration. Histo pathological examination was also performed. IHb in the DSS group incr eased with time; on the 7th day, the value was 126.9 +/- 8.32, while t hat in the control group was 85.0 +/- 4.14, IHb in the DSS group being significantly increased (P < 0.02). ISO2 in the DSS group was lower t han that in the control group, and on the 7th day, was significantly l ower in the DSS group (25.7 +/- 1.34) than in the control group (33.4 +/- 1.77) (P < 0.01). No changes in Flow were observed in either the D SS or the control group during the administration period, and no signi ficant difference in Flow was found between the two groups. On histopa thological examination, we observed a time-dependent increase in the i nfiltration of inflammatory cells in the ascending colon of rats treat ed with DSS, but changes such as erosion and ulceration were not found in the superficial layer of the mucosa. No histopathological changes were found in the control animals. In the early phase of the experimen tal colitis, hemodynamic alterations in the colonic mucosa were alread y present at the time the slight histopathological changes developed. These observations seemed to indicate the involvement of hemodynamic a lterations in the subsequent tissue injury.