Abstract
Electrothermal atomic absorption spectroscopy was employed for measuring barium in β-cell-rich pancreatic islets microdissected from ob/ob-mice. Both the uptake and efflux of barium displayed two distinct phases. There was a 4-fold accumulation of barium into intracellular stores when its extracellular concentration was 0.26 mM. Unlike divalent cations with more extensive intracellular accumulation, the washout of Ba2+ was not inhibited by d-glucose. Ba2+ served as a substitute for Ca2+ both in maintaining the glucose metabolism after removal of extracellular Ca2+ and making it possible for glucose to stimulate insulin release. Furthermore, Ba2+ elicited insulin release in the absence of glucose and other secretagogues. The latter effect was reversible and was markedly potentiated under conditions known to increase the β-cell content of cyclic AMP. It is likely that the observed actions of Ba2+ are mediated by Ca2+, since Ca2+-dependent regulatory proteins, such as calmodulin, apparently cannot bind Ba2+ specifically.
Original language | English (US) |
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Pages (from-to) | 320-328 |
Number of pages | 9 |
Journal | BBA - Molecular Cell Research |
Volume | 720 |
Issue number | 3 |
DOIs | |
State | Published - Jun 8 1982 |
Keywords
- (Pancreatic β-cell)
- Ba accumulation
- Insulin secretion
- Stimulus-secretion coupling
ASJC Scopus subject areas
- Biophysics
- Cell Biology
- Molecular Biology
- Medicine(all)