PMID: 6371115Feb 1, 1984

Effect of extracellular phosphate on Ca2+ and K+ fluxes in pancreatic islets

Journal of Endocrinological Investigation
P LebrunA Herchuelz

Abstract

The idea that a lowering in cytosolic Ca2+ concentration may cause a decrease in K+ conductance in the pancreatic B-cell was tested by investigating the effect of a high extracellular phosphate concentration on 45Ca and 86Rb efflux from prelabelled rat pancreatic islets. Whether in the absence or presence of glucose, 20 mM phosphate tended to decrease 45Ca efflux. This effect was not suppressed in the absence of extracellular Ca2+, at least in glucose-deprived islets, suggesting that it may reflect a fall in cytosolic Ca2+ concentration. The administration of phosphate failed, however, to decrease 86Rb efflux from the islets. In the presence of extracellular Ca2+, 20 mM phosphate also failed to stimulate insulin release from islets perifused at low glucose concentration and inhibited insulin release stimulated by a high glucose concentration. These data indicate that the sequestration of Ca2+ in intracellular organelles and concomitant decrease in cytosolic Ca2+ concentration, as presumably provoked by a rise in extracellular phosphate concentration, is not sufficient to simulate the effect of glucose on K+ conductance.

References

Apr 1, 1979·Metabolism: Clinical and Experimental·W J MalaisseJ C Hutton
Oct 15, 1979·The Biochemical Journal·L M Russell, H Rosenberg
Nov 1, 1977·FEBS Letters·A C BoscheroW J Malaisse
Jan 18, 1978·The Journal of Membrane Biology·W J MalaisseG Somers
Sep 1, 1979·The American Journal of Physiology·B Ribalet, P M Beigelman
Apr 1, 1974·Proceedings of the National Academy of Sciences of the United States of America·A L Lehninger
Jan 1, 1981·The American Journal of Physiology·B J FrankelG M Grodsky
Jul 16, 1982·Biochemical and Biophysical Research Communications·P LebrunA Herchuelz
Jan 1, 1980·Annals of the New York Academy of Sciences·J E Lever
Jun 1, 1981·The Journal of Physiology·A R Carpinelli, W J Malaisse
Dec 15, 1981·Biochemical Pharmacology·P LebrunA Herchuelz

Citations

Oct 15, 1984·Experientia·W J MalaisseA Sener

Related Concepts

Metazoa
Calcium
Cell Membrane Permeability
Cytoplasmic Matrix
Electric Conductivity
Anhydrous Dextrose
Insulin B Chain
Islets of Langerhans
Perfusion
Orthophosphate

Related Feeds