Effect of sodium pyridinethione on the uptake and distribution of nickel in rats,ferrets and guinea-pigs

Oral administration of sodium pyridinethione together with Ni²⁺ (using ⁶³Ni²⁺ as a tracer) to rats, ferrets and guinea-pigs produced highly increased tissue levels of the metal in several tissues in comparison with animals given the Ni²⁺ alone. Ni²⁺ forms a lipophilic complex with pyridinethione and it can be assumed that a facilitated passage of the Ni²⁺ across the cellular membranes of various tissues is important for the observed effects. Pigmented tissues (e. g. the eye melanin), the pancreatic islets, the nervous system and striated muscles showed high levels of Ni²⁺ in animals given sodium pyridinethione. However, in some instances marked species differences were observed. Thus, microautoradiography indicated an uptake of Ni²⁺ both in the β- and α-cells in the pancreatic islets in the rat, whereas in the guinea-pig only some cells (probably the α-cells) accumulated high levels of Ni²⁺. In the ferret sodium pyridinethione induced a high uptake of Ni²⁺ in the heart muscle, which was not seen in the other species. The Ni²⁺ is probably taken up in the various tissues complexed to pyridinethione. Within the tissues the complex may dissociate and the Ni²⁺ may bind to some endogeneous tissue components. The affinity of the Ni²⁺ for the endogeneous ligands in relation to the affinity for the pyridinethione may be of importance for the effects on the disposition of the Ni²⁺. The species variations may be related to differences in the structural conformations of the endogeneous Ni²⁺-binding ligands. Received: 25 October 1993/Accepted: 25 January 1994