Mineral metabolismMagnesium and the parathyroidVetter, Thorsten; Lohse, Martin J. Author Information Institute for Pharmacology and Toxicology, Würzburg, Germany Correspondence to Martin J. Lohse, Institut für Pharmakologie und Toxikologie, Versbacher Straße 9, 97078 Würzburg, Germany. Tel: +49 931 201 48400; fax: +49 931 201 48539; e-mail: [email protected] Abbreviations CaR: calcium-sensing receptor (also termed cation-sensing receptor) DCT: distal convoluted tubule PKA: protein kinase A PKC: protein kinase C PTH: parathyroid hormone Current Opinion in Nephrology and Hypertension 11(4):p 403-410, July 2002. Buy Abstract The serum levels of parathyroid hormone and magnesium depend on each other in a complex manner. The secretion of parathyroid hormone by the parathyroid is physiologically controlled by the serum calcium level, but magnesium can exert similar effects. While low levels of magnesium stimulate parathyroid hormone secretion, very low serum concentrations induce a paradoxical block. This block leads to clinically relevant hypocalcemia in severely hypomagnesiemic patients. The mechanism of this effect has recently been traced to an activation of the α-subunits of heterotrimeric G-proteins. This activation mimicks activation of the calcium sensing receptor and thus causes inhibition of parathyroid hormone secretion. In addition to the effects of magnesium on parathyroid hormone secretion, parathyroid hormone in turn regulates magnesium homeostasis by modulating renal magnesium reabsorption. The distal convoluted tubule is of crucial importance for parathyroid hormone-regulated magnesium homeostasis. © 2002 Lippincott Williams & Wilkins, Inc.