title: Effect of parathyroid hormone and parathyroid hormone fragments on the intracellular ionized calcium concentration in an osteoblast cell line.
abstract: In the present study the effect of parathyroid hormone and parathyroid hormone fragments on the intracellular ionized calcium concentration in an osteoblastic cell line (UMR 106-01) is examined. In these cells the intact hormone, bPTH(1-84) and three fragments (bPTH(1-34), hPTH(1-34) and bPTH(3-34) induce an initial increase of the ionized calcium concentration [( Ca2+]i). The increase of the [Ca2+]i due to bPTH(1-84) is more pronounced and of longer duration compared to the increase due to PTH fragments. For two parathyroid hormone fragments with a modified amino acid sequence [( Nle-8,Nle-18,Tyr-34]bPTH(1-34), [Nle-8,Nle-18,Tyr-34]bPTH(3-34], no effect was found. Our observations suggest: (1) a second messenger role for intracellular ionized calcium in the action of bPTH(1-84) in osteoblasts; (2) a functional role for the COOH-terminal part in the action of bPTH(1-84); and (3) the existence of a specific part of the hormone being responsible for the increase of the intracellular ionized calcium concentration.
mesh_terms: D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D004533:Egtazic Acid / Q000494:pharmacology; D007700:Kinetics; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D051381:Rats; D015290:Second Messenger Systems; D013050:Spectrometry, Fluorescence; D019379:Teriparatide; D013917:Thrombin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D010281:Parathyroid Hormone; D010446:Peptide Fragments; D019379:Teriparatide; C025076:parathyroid hormone (1-34), bovine; D000001:Calcimycin; C031617:parathyroid hormone (3-34); D004533:Egtazic Acid; D013917:Thrombin; D002118:Calcium