title: Hormone-stimulated Mg(2+) accumulation into rat hepatocytes: a pathway for rapid Mg(2+) and Ca(2+) redistribution.
abstract: Many diseases such as cardiac arrhythmia, diabetes, and chronic alcoholism are associated with a marked decrease of plasma and parenchymal Mg(2+), and Mg(2+) administration is routinely used therapeutically. This study uses isolated rat hepatocytes to ascertain if and under which conditions increases in extracellular Mg(2+) result in an increase in intracellular Mg(2+). In the absence of stimulation, changing extracellular Mg(2+) had no effect on total cellular Mg(2+) content. By contrast, carbachol or vasopressin administration promoted an accumulation of Mg(2+) that increased cellular Mg(2+) content by 13.2 and 11.8%, respectively, and stimulated Mg(2+) uptake was unaffected by the absence of extracellular Ca(2+). Mg(2+) efflux resulting from stimulation of alpha- or beta-adrenergic receptors operated with a Mg(2+):Ca(2+) exchange ratio of 1. These data indicate that cellular Mg(2+) uptake can occur rapidly and in large amounts, through a process distinct from Mg(2+) release, but operating only upon specific hormonal stimulation.
authors.affiliation: School of Medicine, Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106, USA.
authors.forename: Theresa E
authors.initials: TE
authors.lastname: Fagan
authors.forename: Antonio
authors.initials: A
authors.lastname: Scarpa
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D017136:Ion Transport / Q000187:drug effects; D007545:Isoproterenol / Q000494:pharmacology; D008274:Magnesium / Q000378:metabolism*; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats
chemical_list: D000316:Adrenergic alpha-Agonists; D000318:Adrenergic beta-Agonists; D001127:Arginine Vasopressin; D010656:Phenylephrine; D015124:8-Bromo Cyclic Adenosine Monophosphate; D002217:Carbachol; D008274:Magnesium; D007545:Isoproterenol; D002118:Calcium; D004837:Epinephrine