title: Regulatory effects of zinc and copper on the calcium transport system in rat liver nuclei. Relation to SH groups in the releasing mechanism.
abstract: In isolated hepatic nuclei, the heavy metals Zn2+ and Cu2+ (10 microM) inhibited Ca2+ uptake and caused a prompt release of Ca2+ from preloaded nuclei in a concentration-dependent manner, with Zn2+ being more effective than Cu2+. The sulfhydryl group reducing agent dithiothreitol (DTT) protected the nuclei from the effects of heavy metals; DDT (1 mM) almost completely blocked Zn(2+)- or Cu(2+)-induced Ca2+ release and inhibition of Ca2+ uptake. The sulfhydryl modifying reagent N-ethylmaleimide (NEM; 0.2 mM) also caused Ca2+ release, but it did not have an appreciable effect on Ca2+ uptake. Furthermore, in the presence of NEM heavy metals did not evoke Ca2+ release. The present study demonstrates that Zn2+ and Cu2+ have a stimulatory effect on Ca2+ release from isolated rat liver nuclei, and that the SH group may play an important role in the Ca(2+)-releasing mechanism in liver nuclei.
authors.affiliation: Laboratory of Metabolism and Endocrinology, Graduate School of Nutritional Sciences, University of Shizuoka, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yamaguchi
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002467:Cell Nucleus / Q000187:drug effects; D003300:Copper / Q000494:pharmacology*; D004229:Dithiothreitol; D004305:Dose-Response Relationship, Drug; D004566:Electrodes; D005033:Ethylmaleimide / Q000494:pharmacology; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D010477:Perfusion; D051381:Rats; D017208:Rats, Wistar; D013438:Sulfhydryl Compounds / Q000378:metabolism*; D015032:Zinc / Q000494:pharmacology*
chemical_list: D013438:Sulfhydryl Compounds; D003300:Copper; D000255:Adenosine Triphosphate; D015032:Zinc; D005033:Ethylmaleimide; D002118:Calcium; D004229:Dithiothreitol