Format

Send to

Choose Destination
Biochim Biophys Acta. 1990 Oct 15;1055(1):82-6.

Insulin secretagogues induce Ca(2+)-like changes in cytoplasmic Mg2+ in pancreatic beta-cells.

Author information

1
Department of Medical Cell Biology, Uppsala University, Sweden.

Abstract

The effects of insulin secretagogues on the cytoplasmic Mg2+ concentration ([Mg2+]i) of pancreatic beta-cells were studied in suspensions and in individual beta-cells using dual-wavelength fluorometry and the indicator mag-fura-2. Average [Mg2+]i was in the 800-900 microM range in a medium containing 3 mM glucose. When the sugar concentration was raised to 20 mM, the cells reacted with an initial lowering of [Mg2+]i followed by an increase. The sugar apparently also stimulated leakage of the Mg2+ indicator. Addition of 100 microM tolbutamide or raising the K+ concentration by 25 mM caused relatively rapid increases of [Mg2+]i. Methoxyverapamil prevented the [Mg2+]i-increasing actions of glucose, K+ and tolbutamide. The greatest change in [Mg2+]i was obtained when beta-cells were exposed to 100 microM carbachol. In this case there was a more than 10% lowering, which was reversed upon removal of the agonist. Measurements of [Mg2+]i are important not only for understanding fluctuations of this ion, but may also aid to elucidate the mechanisms involved in the regulation of cytoplasmic Ca2+.

PMID:
2223873
DOI:
10.1016/0167-4889(90)90094-t
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center