Urinary excretion of enteral iohexol in rats with intestinal ischaemia. The influence of size of ischaemic area and duration of exposure to contrast medium.

The urinary excretion of iohexol instilled via orogastric tube was evaluated in rats with ischaemic intestinal segments, simple bowel ligature, and normal bowel. The rats were observed for periods of 1, 2, 3, 4, 5, 6, and 8 h, respectively, after the instillation of 3 ml of contrast medium. Radiographs and blood and urine tests were taken at the end of each observation period. Distinct radiographic opacification of the urinary bladder of the rats with intestinal ischaemia was demonstrated already 2 h after the administration of contrast medium and onwards. Concurrently high iodine concentrations in the urine and serum were measured by an X-ray fluorescence technique. The bladder opacity and iodine levels in the urine varied in close proportion to the length of ischaemic bowel irrespective of the duration of enteric exposure to contrast medium. Overall mean urinary iodine levels were approximately 11 and 32 times that of normal controls in animals with ischaemic bowel segments of 15 and 45 cm, respectively. In comparison, the overall mean serum level in rats with 45-cm ischaemic segments was 16 times that of normals. The clinical implications are discussed.