[Tissue distribution of red blood cells treated with X-ray contrast media in rats]

Tissue distribution of red blood cells (RBC) that were treated with X-ray contrast media was investigated in rats. The contrast medium mixed with an equivolume of 51Cr-labelled RBC was administered to the internal carotid artery in a dose of 200 microliters/rat; and the radioactivity in the brain, lung and spleen were determined. The contrast medium mixed with an equivolume of blood was administered to the right atrium in a dose of 4 ml/kg, and the hemoglobin content in the lung and changes in pulmonary and circulatory functions were determined. In the ionic contrast medium (meglumine diatrizoate)-treated group, the radioactivity in the brain remained 30 to 50 times higher compared with the nonionic contrast medium (iopamidol)- and saline-treated group until 15 min after infusion. The radioactivity in the spleen increased and the radioactivity and hemoglobin content in the lung decreased time-dependently in the diatrizoate-treated group, whereas iopamidol- and saline-treated groups exhibited constantly low values during the experimental period. Changes in the airway pressure, pulmonary arterial pressure, systemic blood pressure and heart rate were similar after intra-atrial administration of diatrizoate mixed with blood and diatrizoate mixed with saline. These results suggest that the ionic contrast medium affects the RBC and causes a microcirculatory disturbance in the brain.