Plasma zinc as an indicator of zinc status in rats

Standard zinc solutions for the atomic absorption analysis of rat plasma were prepared to contain 14% (w/v) of sucrose. In this way the problems of sample nebulization were overcome with a minimum of manipulation before assay. 2. Plasma Zn concentrations in rats were found to fall by approximately 40% (from 1.2 to 0.7 μg/ml) after 1 d on a Zn-deficient (< 0.25 ppm) diet. Thereafter, the fall became less marked and after 5 d the concentrations usually varied between 0.4 and 0.6 μg/ml. 3. A single oral dose (20–200 μg) of Zn was reflected in high plasma Zn concentrations in the depleted rats 1.75 h after dosing, but to a much lesser extent in animals receiving 10–60 ppm Zn in their diet before dosing. 4. It is suggested that the plasma Zn response to a single oral dose of zinc sulphate may provide a useful method for the detection of a subnormal Zn status in individual farm animals without the necessity of determining breed norms.