[Effect of calcium on N-terminal truncation of PTH in human parathyroid cells].
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.
Kawata
Takehisa
T
Department of Metabolism, Endocrinology and Molecular Medicine, Osaka City University Graduate School of Medicine.
Imanishi
Yasuo
Y
Kobayashi
Keisuke
K
Tahara
Hideki
H
Ishimura
Eiji
E
Inaba
Masaaki
M
Nishizawa
Yoshiki
Y
Takemoto
Yoshiaki
Y
Onoda
Naoyoshi
N
Okuno
Senji
S
Ishikawa
Tetsuro
T
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
D010281:Parathyroid Hormone; D010446:Peptide Fragments; C414937:parathyroid hormone (7-84); D002118:Calcium