In an attempt to elucidate the acute toxic effects on rat tissue induced by barium sulfate, the present study was undertaken in male Sprague-Dawley rats. We made incisions on the midabdomen of the rats and administered the barium sulfate (4 ml/kg) into the peritoneal cavity. The control group was given a similar volume of physiologic saline. The animals were sacrificed 1, 3, 5, 7, 14, 28, 42, and 56 days after barium sulfate administration. The lung, liver, kidney, spleen, adrenal gland, thymus, pancreas, salivary gland, and mesenteric lymphnode were microscopically examined.
The results were as follows:
1. The barium induced toxicity was most prominent in the spleen, showing diffuse hemorrhagic necrosis with the loss
of red or white pulp structures, and focal calcification on day 1 and 3. On day 14, the spleen showed regeneration
activity with reappearance of red and white pulps, and with diffuse scattered macrophages. On day 28, the number of
macrophages gradually decreased, but macrophages remained in the parenchyma after 42days after barium treatment.
2. The barium toxicity to the liver and lung was proportional to the experimental duration. In the liver, focal hemorrhagic
necrosis and macrophage infiltration was observed on day 1 and 3. Thereafter the degree of macrophage infiltration became more severe, and chronic hepatitis was found 42 days after barium treatment. The lungs showed interstitial pneumonitis on day 7, followed by the features of lobular pneunomia 28 days after barium treatment.
3. The kidney showed focal to multifocal areas of dilatation of proximal tubules, and detachment of the tubular lining
cells on the early period of this experiment. The degree of renal changes was propotional to the experimental days, and interstitial nephritis was observed on day 42.
4. The adrenal gland showed diffuse hemorrhagic necrosis on day 1, coagulation necrosis on day 3, respectively.
Fourteen days after barium treatment, incomplete recovery with diffuse infiltration of macrophages was observed. On
day 28, the structure of adrenal gland was returned to normal, but diffuse macrophage infiltration and focal calcification
remained in the parenchymal tissue.
5. The changes in the other organs showed chronic pancreatitis, chronic lymphadenitis to granulomatous inflammation
in mesentric nodes, and chronic inflammatory features in the salivary glands. In conclusion, these experimental results suggest that barium toxicity was most prominent in the spleen, and that the barium sulfate injected into the peritoneal cavity is partially absorbed via the lymphatic system. The diaphragmatic part of peritoneum plays an important role in the process.
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