Action of cobalt compounds on vascular permeability, mast cells and blood clotting in rats and rabbits

Acute exposure to cobalt induces transient methemoglobinuria in rats

We observed transient excretion of dark-brown urine after acute exposure to cobalt in rats and investigated the mechanism of it. We injected cobalt into rats s.c. at a dose of 15 mg/kg and collected urine, peripheral blood, and organ samples at the indicated times after injection. Biochemical and histopathological examinations of these samples were conducted. Obvious macroscopic and biochemical methemoglobinuria was observed just after injection of cobalt, but the level of urinary methemoglobin decreased gradually, almost disappearing by 24 h. The levels of cobalt in peripheral blood and urine showed a very similar pattern to that of methemoglobinuria. Neither anemia nor bilirubinemia was observed, indicating no extrarenal intravascular hemolysis. Pathological examination of the kidneys revealed that the glomerular capillaries were filled with red blood cells at 1 h after injection. Electron microscopy showed deformed red blood cells in the glomerular capillaries and condensed hemoglobin in Bowman's capsule that passed through the basement membrane. There were no trends toward increases in plasma levels of creatinine or blood urea nitrogen. These results indicate that exposure to cobalt induces transient methemoglobinuria through the lysis of red blood cells and oxidation of iron in hemoglobin at the glomerular capillaries without causing renal dysfunction.

The distribution in mice of radioactive cobalt administered by two different methods

The short time distribution of 58Co in mice that received a 58CoCl2 solution intravenously or intraperitoneally was examined by means of scintillation measurements. The serum, kidney, pancreas, spleen, liver, and heart were analyzed. Statistically significant differences in the distribution pattern after intraperitoneal and intravenous administration were noted for serum, kidney, liver, and heart 1 h after injection and for kidney, liver, and heart 5 h after injection. Only the heart showed a significant difference between the two administration methods 24 h after injection. Intravenous injections gave less variation between animals of the 58Co distribution pattern than intraperitoneal injections.