These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Effects of extracellular calcium and magnesium on cytosolic calcium concentration in Fura-2-loaded bovine parathyroid cells.
    Author: Chen CJ, Anast CS, Posillico JT, Brown EM.
    Journal: J Bone Miner Res; 1987 Aug; 2(4):319-27. PubMed ID: 3455617.
    Abstract:
    A newly developed calcium-sensitive dye, Fura-2, was employed in dispersed bovine parathyroid cells to study the effects of extracellular calcium and magnesium on cytosolic calcium concentration and parathyroid hormone (PTH) release. In comparison with control cells, Fura-2-loaded parathyroid cells showed the same maximal rate of PTH release, set-point for extracellular Ca++ (the calcium concentration producing half of the maximal inhibition of PTH release), and maximal inhibition of PTH release (71.6%) by high extracellular Ca++. At an extracellular Mg++ concentration of 0.5 mM, raising extracellular Ca++ in a stepwise fashion from 0.5 mM to 2.0 mM produced a dose-dependent, statistically significant (p less than 0.01) increase in cytosolic Ca++ from 198 +/- 24 nM (0.5 mM Ca++) to 411 +/- 21 nM (2.0 mM Ca++) which closely paralleled the concomitant decrease in PTH release. An elevation of extracellular Mg++ from 0.5 mM to 5 mM, at an extracellular Ca++ of 0.5 mM, resulted in a transient spike of cytosolic Ca++ which lasted for approximately 30 seconds, followed by a small but stable increase in the cytosolic Ca++ concentration (174 +/- 7 nM vs. 237 +/- 10 nM, n = 4, p less than 0.01). Prior removal of extracellular calcium by addition of an excess of EGTA did not abolish the transient spike induced by high extracellular magnesium concentrations in Fura-2-loaded cells, suggesting that this rapid increase in cytosolic Ca++ arises, at least in part, from intracellular stores of Ca++. This is supported by the observation that pretreating cells with ionomycin resulted in disappearance of the magnesium-induced spike.(ABSTRACT TRUNCATED AT 250 WORDS)
    [Abstract] [Full Text] [Related] [New Search]