KINETICS OF SELENIUM INCORPORATION INTO TISSUES OF FEMALE MALLARD DUCKS

Selenium is essential for both mammalian and avian species, although i ts metabolism in birds has been less thoroughly studied. Little inform ation has been available on the kinetics of selenium in birds, especia lly as it relates to the teratogenicity seen in waterfowl consuming ex cessive amounts. This study describes the pharmacokinetics of small am ounts of Se-75 as selenious acid injected into female mallard ducks. L abeled selenium was injected into a wing vein of restrained animals an d tissues taken at five different time points up to 24 h post-injectio n. Selenium levels as percent of injected dose were determined in live r, kidney, heart, lung, adrenals, thyroid, spleen, pancreas, ovaries, intestine, muscle and plasma. Estimates of kinetic parameters (uptake and elimination rates, time of maximum concentration and maximum conce ntration) were obtained with a non-linear kinetics computer program (P CNON-LIN SCI Software, Lexington, KY). Results showed four basic patte rns of distribution, uptake and elimination. Visceral tissues exhibite d a triphasic pattern with a rapid rise, a decline followed by a disti nctive increase in levels between the last two time points. Brain upta ke was continuous over the 24 h. Plasma rose rapidly and then declined to a constant level. The ovaries as a tissue of interest relating to the teratogenic effects of selenium showed the greatest relative incre ase at 24 h, suggesting kinetic mechanisms consistent with a pathway t hat might lead to accumulation of toxic levels and teratogenic effects during embryo development. (C) 1997 Elsevier Science Ieland Ltd.