Glucose reduces both Rb+ influx and efflux in pancreatic islet cells.
Microdissected, beta-cell-rich pancreatic islets from ob/ob mice were used in studies of 86Rb+ transport. D-Glucose (20 mM) induced a biphasic reduction in 86Rb+ efflux. The reduction stabilized within 10 min at 34% of the efflux rate at zero glucose. The initial 86Rb+ uptake (5 min) was dose-dependently reduced by ouabain with maximum inhibition at 1 mM. D-Glucose (20 mM) did not affect the ouabain-sensitive 86Rb+ influx but markedly reduced (48%) the ouabain-resistant isotope influx. The results suggest that D-glucose does not affect the Na+/K+ pump in pancreatic beta-cells and that the glucose-sensitive K+-transporting modalities (K+ channels) in the beta-cells can mediate both inward and outward K+ flux.
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology*; D066298:In Vitro Techniques; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D008820:Mice, Obese; D012413:Rubidium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D000254:Sodium-Potassium-Exchanging ATPase; D005947:Glucose; D012413:Rubidium