Decrease of plasma vitamin A, albumin and zinc in cadmium-treated rats

Male rats of the Wistar strain were injected subcutaneously with a total dose of 4.5 mg cadmium (Cd) per kg body weight. The first groups (Sc-1) was injected with 18 doses of 0.25 mg/kg, the second group (Sc-II) was injected with 9 doses of 0.50 mg/kg, and the third group (Sc-III) with 2 doses of 2.25 mg/kg. Another group was given water containing 75 ppm Cd for 68 days and 50 ppm for the ensuing 75 days. The plasma concentration of vitamin A (VA) was statistically decreased by the subcutaneous injections of Cd, but the liver concentration of VA was not altered. The fractionated injection of the total Cd apparently reduced the toxicity of Cd on VA metabolism. The decrease of plasma albumin was highly correlated with the decrease of plasma VA. The relative coefficient between them was calculated as 0.812 (n = 34, P less than 0.01) with all of the groups. the relative coefficient between plasma VA and zinc (Zn) was lower than that between plasma VA and albumin but was statistically significant (r = 0.697, P less than 0.01). These results may indicate the involvement of hepatic damage in Cd intoxications. The decrease of plasma VA, however, could not be explained by the Zn deficiency of the liver. To clarify the role of Zn in VA metabolism, the secretion mechanisms of them should be investigated in the liver.