Inhibition of sodium-dependent taurine transport in red blood cells from the marine polychaete, Glycera dibranchiata, after exposure to mercury.

Abstract

An earlier study (Chen and Preston, 1987) demonstrated that HgCI 2 at low concentrations (20 ~M) inhibited the transport of the amino acid, taurine, by the hemoglobin containing coelomocytes (red blood cells, RBCs) of the marine polychaete, Glycera dibranchiata. These red cells maintain an internal concentration of 190 mM taurine compared with an external concentration in the coelomic fluid of approximately 0.2 mM. This high gradient appears to be generated via a Na and CI dependent active transport system which is specific for taurine and closely related analogues (Preston and Chen, 1986; Chen and Preston, 1986). This taurine transport system resembles other taurine transport systems observed in heart and kidney tissue (Awapara and Berg, 1985; Wolff et al, 1985). It appears that Glycera RBCs provide an excellent model system to study the mechanism of heavy metal inhibition of transport function. We proposed that one possible mechanism for the action of HgCI 2 is that this molecule binds to sulfhydryl groups in the Na binding site of the transport protein. In order to test this hypothesis we conducted a series of kinetic studies to analyze in more detail the interaction oi Na and Hg with the transport system. In addition, we conducted experiments to determine whether the effects of HgCI 2 treatment could also be due to generalized changes in cellular permeability.