[Mechanism of beta 2-microglobulinuria in experimental chronic cadmium intoxication]

Natural history of cadmium health effects was studied on monkeys and rabbits given cadmium chloride orally or subcutaneously for a long period: 6 male monkeys were given pelleted food containing 100 micrograms Cd/g over a period of 180 weeks, 15 male rabbits pelleted food containing 300 micrograms Cd/g over a period of 24 weeks, 13 male rabbits daily subcutaneous injections at a dose level of 0.5 mg Cd/kg over a period of 44 weeks, and 23 rabbits subcutaneous injections at a dose level of 0.5 mg Cd/kg 6 times a week over a period of 21 weeks, respectively. Sodium dodecyl polyacrylamide gel electrophoresis and silver staining (detection limit of protein: 80 micrograms/dl) revealed that urinary protein of molecular weight 12,000 (probably beta 2-microglobulin) increased slightly prior to the appearance of proteinuria, glycosuria or aminoaciduria. Remarkable increase in urinary protein of molecular weight 12,000 was observed by Amidoblack 10 B staining (detection limit: 4 mg/dl) around the time when renal dysfunctions appeared. The above result might suggest that the remarkable increase in urinary beta 2-microglobulin is associated with renal dysfunctions, while the slight increase is caused by other mechanisms than renal dysfunctions.