Effect of extracellular sodium removal upon 86Rb outflow from pancreatic islet cells.
The present study was undertaken to characterize the effect of extracellular Na+ removal on 86Rb outflow from perifused rat pancreatic islets. Complete Na+ omission inhibited 86Rb outflow whether the islets were perifused in the presence or in the absence of extracellular Ca2+. Ouabain (1 mM) did not reduce the inhibitory effect of Na+ deprivation, whilst diphenylhydantoin (72.9 microM) mimicked the Na+-removal-induced fall in 86Rb outflow. Glucose (16.7 mM) lost its capacity to inhibit 86Rb outflow when the perifusate was deprived of extracellular Na+. These results indicate that Na+ omission reproduces the inhibitory effect of glucose on 86Rb outflow. The reduction in 86Rb outflow recorded after Na+ deprivation could be mediated by an intracellular acidification and/or a decrease in the intracellular Na+ activity. It is tempting to speculate that the capacity of glucose to reduce the B-cell Na+ content may participate in the process by which the sugar decreases K+ permeability.
Lebrun
P
P
Laboratory of Pharmacology, Brussels Free University School of Medicine, Belgium.
Plasman
P O
PO
Herchuelz
A
A
D000643:Ammonium Chloride / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D005110:Extracellular Space / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D010042:Ouabain / Q000494:pharmacology; D010672:Phenytoin / Q000494:pharmacology; D011803:Quinine / Q000494:pharmacology; D051381:Rats; D012414:Rubidium Radioisotopes / Q000378:metabolism*; D012964:Sodium / Q000502:physiology*; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D012414:Rubidium Radioisotopes; D013757:Tetraethylammonium Compounds; D000643:Ammonium Chloride; D010042:Ouabain; D010672:Phenytoin; D019789:Tetraethylammonium; D012964:Sodium; D011803:Quinine; D005947:Glucose; D002118:Calcium