Interaction of Hg, Ca, Mg, Na and Se with intestinal absorptive functions in marine fish

Abstract

Heavy metals comprise a major category of pollutants released into coastal waters from natural and man-made sources. They bind to and accumulate in marine organisms and amplify through the food chain. Their lethal doses and sublethal effects in different organisms have been studied. We have shown that among a series of heavy metal compounds tested, HgCl2and CH3HgCl inhibit the intestinal absorption of essential amino acids (e.g. leucine, isoleucine, methionine, lysine) in marine fish. HgCl2is the more potent inhibitor. We examined the interactions of Ca⁺⁺, Mg⁺⁺, Na⁺and Se⁴⁺with the HgCl2inhibitory effect. The results show that leucine transport requires Ca⁺⁺, Mg⁺⁺and Na⁺. Hg⁺⁺severely inhibits this amino acid transport. The interaction between Hg⁺⁺inhibition and the absence of Ca⁺⁺, Mg⁺⁺or Na⁺is neither additive nor synergistic; there is some inter-cation antagonism. Se⁴⁺causes a small inhibition which is additive to Hg⁺⁺inhibition.