Behavior of radiozinc in rat plasma

Abstract

This series of studies was undertaken to determine the behavior of Zn⁶⁵ when injected intravenously as the inorganic ion. A clearance curve for Zn⁶⁵ similar to those of other workers was obtained. It was found that the decrease in clearance and distribution of Zn⁶⁵ was not in direct proportion to the decrease in specific activity. Upon extraction of loosely bound zinc from plasma with dithizone-acetone virtually all of the injected Zn⁶⁵ could be removed up to 1 hr after intravenous injection. However, extraction of the unbound zinc ion demonstrated that more than 90% of the Zn⁶⁵ is bound to protein within the first 3 min after addition of Zn⁶⁵. Dialysis of Zn⁶⁵ against plasma protein showed the Zn⁶⁵ ion is removed by plasma from solution by direct binding to nondialyzable plasma components. Irradiation of rats with supralethal dosages of X ray followed by subsequent injection of Zn⁶⁵ demonstrated that clearance of Zn⁶⁵ from plasma is unaffected by this major alteration of the metabolic state of the animal.