EurekaMag.com logo
+ Site Statistics
References:
52,725,316
Abstracts:
28,411,598
+ Search Articles
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on Google+Follow on Google+
Follow on LinkedInFollow on LinkedIn

+ Translate

Regulation of hormone secretion and cytosolic calcium by extracellular calcium in parathyroid cells and c cells role of voltage sensitive calcium channels


Archives of Biochemistry & Biophysics 265(1): 128-135
Regulation of hormone secretion and cytosolic calcium by extracellular calcium in parathyroid cells and c cells role of voltage sensitive calcium channels
The two dihydropyridine enantiomers, (+)202-791 and (-)202-791, that act as voltage-sensitive Ca2+ channel agonist and antagonist, respectively, were examined for effects on cytosolic Ca2+ concentrations ([Ca2+]i) and on hormone secretion in dispersed bovine parathyroid cells and a rat medullary thyroid carcinoma (tMTC) cell line. In both cell types, small increases in the concentration of extracellular Ca2+ evoked transient followed by sustained increases in [Ca23+]i, as measured with fura-2. Increases in [Ca2+]i obtained by raised extracellular Ca2+ were associated with a stimulation of secretion of calcitonin (CT) and calcitonin gene-related peptide (CGRP) in rMTC cells, but an inhibition of secretion of parathyroid hormone (PTH) in parathyroid cells. The Ca2+ channel agonist (+)202-791 stimulated whereas the antagonist (-)202-791 inhibited both transient and sustained increases in [Ca2+]i induced by extracellular Ca2+ in rMTC cells. Secretion of CT and CGRP was correspondingly enhanced and depressed by (+)202-791 and (-)202-791, respectively. In contrast, neither the agonist nor the antagonist affected [Ca2+]i and PTH secretion in parathyroid cells. Depolarizing concentrations of extracellular K+ increased [Ca2+]i and hormone secretion in rMTC cells and both these responses were potentiated or inhibited by the Ca2+ channel agonist or antagonist, respectively. The results suggest a major role of voltage-sensitive Ca2+ influx in the regulation of cytosolic Ca2+ and hormone secretion in rMTC cells. Parathyroid cells, on the other hand, appear to lack voltage-sensitive Ca2+ influx pathways and regulate PTH secretion by some alternative mechanism.


Accession: 006288500



Related references

Regulation of hormone secretion and cytosolic Ca2+ by extracellular Ca2+ in parathyroid cells and C-cells: role of voltage-sensitive Ca2+ channels. Archives of Biochemistry and Biophysics 265(1): 128-135, 1988

Role of calcium ion channels in the regulation of cytosolic calcium ion levels by extracellular calcium ions in rat c cells. Biophysical Journalpart 2: 428a, 1987

Interaction of extracellular calcium and magnesium in the regulation of cytosolic calcium and parathyroid hormone release in dispersed bovine parathyroid cells. Molecular & Cellular Endocrinology 38(2-3): 179-186, 1984

Regulation of parathyroid hormone release and cytosolic calcium by extracellular calcium in dispersed and cultured bovine and pathological human parathyroid cells. Journal of Clinical Investigation 75(1): 49-57, 1985

Neuropeptide y enhances lhrh induced lh release and elevations in cytosolic calcium in rat anterior pituitary cells evidence for involvement of extracellular calcium ion influx through voltage sensitive channels. Endocrinology 127(3): 1487-1494, 1990

Interaction of extracellular calcium and magnesium in the regulation of cytosolic calcium and PTH release in dispersed bovine parathyroid cells. Molecular and Cellular Endocrinology 38(2-3): 179-186, 1984

Interaction between extracellular calcium and endothelin-1 influences parathyroid hormone secretion from bovine parathyroid cells through the increase in intracellular calcium. Mineral and Electrolyte Metabolism 23(2): 113-120, 1997

Osteoclast cytosolic calcium, regulated by voltage-gated calcium channels and extracellular calcium, controls podosome assembly and bone resorption. Journal of Cell Biology 111(6 Pt 1): 2543-2552, 1990

Role of cytosolic calcium in the regulation of cyclic amp content by calcium in bovine parathyroid cells. Clinical Research 33(2 PART 1): 435A, 1985

Characterization of the calcium response to thyrotropin-releasing hormone (TRH) in cells transfected with TRH receptor complementary DNA: importance of voltage-sensitive calcium channels. Molecular Endocrinology 6(9): 1393-1402, 1992