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Stimulation of parathyroid hormone secretion by phorbol esters is associated with a decrease of cytosolic calcium
Author(s) -
Muff R.,
Fischer J.A.
Publication year - 1986
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(86)80087-4
Subject(s) - protein kinase c , calcium , endocrinology , medicine , secretion , chemistry , parathyroid hormone , extracellular , cytosol , activator (genetics) , parathyroid chief cell , stimulation , phorbol , kinase , biology , biochemistry , receptor , enzyme
Unlike in other endocrine systems calcium inhibits parathyroid hormone (PTH) secretion and this inhibition is paralleled by a rise of cytosolic calcium concentration ([Ca] i ). Because of evidence that diglyceride levels and protein kinase C activity are also decreased by high extracellular calcium we have investigated the effects of 12‐ O ‐tetradecanoylphorbol‐13‐acetate (TPA), an activator of protein kinase C, on [Ca] i and PTH secretion using dispersed bovine parathyroid cells. At 1.5 mM medium calcium TPA enhanced PTH secretion and caused reduction of [Ca] i from 639 ± 36 nM (SE) to 335 ± 21 nM ( P < 0.001); at 0.5 mM calcium TPA was ineffective. Moreover, TPA suppressed the rise of [Ca] i evoked by high extracellular calcium. Thus TPA presumably stimulates PTH secretion via activation of protein kinase C, and the lowering of [Ca] i may be a secondary event related to diglyceride availability.