Direct inhibitory effect of amino-terminal parathyroid hormone fragment [PTH(1-34)] on PTH secretion from bovine parathyroid primary cultured cells in vitro.
We have examined the possibility of direct inhibitory effect of PTH(1-34) on PTH secretion in bovine parathyroid cells. As low as 10(-12) M PTH(1-34) completely inhibited low calcium (0.5 mM Ca2+)-stimulated PTH secretion by these cells. In the presence of 1.25 mM Ca2+, 10(-12) M PTH(1-34) inhibited PTH secretion by about 14.3% of the basal value, while 10(-11) M or higher concentration of PTH(1-34) showed potent inhibitory effects equivalent to the inhibitory action of high calcium concentration (2.5 mM Ca2+) on PTH secretion. At 2.5 mM Ca2+, as much as 10(-9) M PTH(1-34) failed to inhibit PTH secretion further. These results suggest that PTH(1-34) might directly, not via calcium concentration, inhibit PTH secretion by parathyroid cells and that a cooperative mechanism could exist between calcium and PTH(1-34) to inhibit PTH secretion.
Fujimi
T
T
Department of Medicine, Kobe University School of Medicine, Japan.
Baba
H
H
Fukase
M
M
Fujita
T
T
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002417:Cattle; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D007700:Kinetics; D010280:Parathyroid Glands / Q000187:drug effects / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D019379:Teriparatide; D013997:Time Factors
D010281:Parathyroid Hormone; D010446:Peptide Fragments; D019379:Teriparatide; D002118:Calcium