Ga3+ inhibits parathyroid hormone release without interacting with the Ca2+ receptor of the parathyroid cell.
Gallium nitrate is an antihypercalcemic agent with established actions on bone. The effects of Ga(NO3)3 on parathyroid hormone (PTH) release, cytoplasmic Ca2+ concentration ([Ca2+]i) and cAMP production of enzymatically dispersed parathyroid cells from bovine as well as normal and pathological human parathyroid glands have now been studied. Ga3+ at 200 microM inhibited PTH release whereas 600 microM NO3- had no effect. The inhibition was additive to that obtained by elevating extracellular Ca2+. Unlike Ca2+, Ga3+ failed to increase [Ca2+]i or reduce cAMP formation. The results indicate that Ga3+ inhibits PTH release by a mechanism other than activation of the cation receptor of the parathyroid cells. This mechanism may contribute also to inhibition by other cations.
Ridefelt
P
P
Department of Medical Cell Biology, Uppsala University, Sweden.
Hellman
P
P
Ljunggren
O
O
Ljunghall
S
S
Akerström
G
G
Rastad
J
J
Gylfe
E
E
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000187:drug effects / Q000378:metabolism*; D002417:Cattle; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D016257:Fura-2; D005708:Gallium / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D010279:Parathyroid Diseases / Q000503:physiopathology; D010280:Parathyroid Glands / Q000187:drug effects / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000378:metabolism*; D010282:Parathyroid Neoplasms / Q000503:physiopathology
D000970:Antineoplastic Agents; D002135:Calcium-Binding Proteins; D010281:Parathyroid Hormone; D005708:Gallium; D000242:Cyclic AMP; D002118:Calcium; D016257:Fura-2; C027235:gallium nitrate