Methylmercury uptake and distribution kinetics in sheepshead minnows, Cyprinodon variegatus, after exposure to Ch3Hg-spiked food.

The distribution kinetics of methylmercury (CH3Hg[II]) was determined in sheepshead minnows (Cyprinodon variegatus) after a single dose of different CH3Hg(II)-spiked food to determine what factors influence the bioavailability, uptake, and redistribution of CH3Hg(II) to various organs of C. variegatus. The kinetics of CH3Hg(II) distribution was measured in the different organs during a period of 0.1 to 35 d after dosage. The CH3Hg(II) distribution kinetics in the different tissues was modeled using a simple multicompartmental pharmacokinetic model, which assumed that blood was the conduit linking the CH3Hg(II) exchange between the different organs. The CH3Hg(II) was taken up into the intestinal tissue within hours after feeding, followed by a slow release to the blood and the other organs of the body. Exchange between the blood and the visceral organs was relatively slow, with maximum CH3Hg(II) uptake in the liver and gill occurring at 1.5 d following dietary exposure. Subsequently, the majority of the CH3Hg(II) was channeled from the viscera to the rest of the body with a substantial lag time after feeding. However, the rate of transfer between tissues in the studies reported here were faster than those measured by others for larger fish.