title: [Effect of calcium on N-terminal truncation of PTH in human parathyroid cells].
abstract: Serum PTH (7-84) is accumulated in patients with secondary hyperparathyroidism. It is also known that serum calcium (Ca) increases the generation of N-terminally truncated forms of parathyroid hormone (PTH). In this study, we examined whether accumulation of PTH (7-84) fraction is a parathyroid glandular origin or not by using primary cultured parathyroid cells from patients with primary and secondary hyperparathyroidism. The Bio-PTH/I-PTH ratio, indicating the ratio of PTH (1-84) to the sum of (1-84) PTH and N-terminally truncated fragment, was suppressed by increase in extracellular Ca2+ concentration for both cultured parathyroid cells prepared from parathyroid adenomas and uremia-associated secondary hyperparathyroidism. There is no difference between the ratios in primary and secondary hyperparathyroidism. These findings suggest that N-terminal truncation is regulated by extracellular Ca2+ concentration in parathyroid cells, but accumulation of PTH (7-84) fragments in patients with secondary hyperparathyroidism is mainly caused by uremia.
authors.affiliation: Department of Metabolism, Endocrinology and Molecular Medicine, Osaka City University Graduate School of Medicine.
authors.forename: Takehisa
authors.initials: T
authors.lastname: Kawata
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Imanishi
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Hideki
authors.initials: H
authors.lastname: Tahara
authors.forename: Eiji
authors.initials: E
authors.lastname: Ishimura
authors.forename: Masaaki
authors.initials: M
authors.lastname: Inaba
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Nishizawa
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Takemoto
authors.forename: Naoyoshi
authors.initials: N
authors.lastname: Onoda
authors.forename: Senji
authors.initials: S
authors.lastname: Okuno
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Ishikawa
mesh_terms: D002118:Calcium / Q000494:pharmacology*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D006801:Humans; D049950:Hyperparathyroidism, Primary / Q000378:metabolism*; D006962:Hyperparathyroidism, Secondary / Q000378:metabolism*; D010280:Parathyroid Glands / Q000166:cytology*; D010281:Parathyroid Hormone / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism*; D014511:Uremia / Q000378:metabolism
chemical_list: D010281:Parathyroid Hormone; D010446:Peptide Fragments; C414937:parathyroid hormone (7-84); D002118:Calcium