Abstract
Urinary protein from five cadmium workers has been examined, two men exposed to cadmium dust and three to cadmium fume. No difference was discernible between the two groups in regard to the quantity of protein excreted (10 to 36 times the average normal) or to the chemical composition and molecular weight of the protein. Cadmium urinary protein exhibits a complex electrophoretic pattern on paper, with five components. These have mobilities similar to the five main fractions of serum. All their molecular weights, however, are in the range 20 to 30,000. Filter paper electrophoresis showed a preponderance of globulins, especially α(2), over albumin. On column electrophoresis, however, a relatively higher proportion of albumin appeared, due probably to a change of mobility of a heat incoagulable protein, which constituted 20 to 25% of the whole. The heat incoagulable protein had a high content of glycine, serine, hexose, methylpentose, and sialic acid. Electrophoretic fractions 1 and 2 of the urinary protein were similarly rich in glycine, serine, hexose, methylpentose, and sialic acid, possibly due to presence of heat incoagulate protein. The presence of two components in fraction 1 became evident from ultracentrifugal studies. Plasma proteins could be demonstrated immunologically in the urine, but the relative proportion present could not be assessed. Urinary proteins associated with cadmium absorption include components of low molecular weight and high carbohydrate content similar to those which have been observed in normal urine. The distinctive feature of the proteinuria appears to be the presence of a low molecular urinary albumin, the origin of which is the subject of further study.