Potassium and chloride fluxes are involved in volume regulation in mouse pancreatic islet cells.
Potassium and chloride transport were measured in beta-cell-rich islets from ob/ob-mice using 36Cl- and 86Rb+ (K+-analogue). Reduction of the osmolarity from the normal 317 mosm l-1 to 180 mosm l-1 reduced the apparent content of K+ and Cl-. Hypo-osmolarity had no effect on the ouabain-sensitive portion of the Rb+ influx (Na+/K+ pump), but reduced the ouabain-resistant portion of the influx. Hypo-osmolarity also strongly increased the Rb+ efflux rate. Both tetracaine (0.5 mM) and glibenclamide (20 microM), which increase the osmotic resistance of pancreatic beta cells, significantly potentiated the reduction in apparent K+ content induced by hypo-osmolarity. This study suggests that the volume regulation in pancreatic beta cells is partly due to K+ and Cl- flux and that glibenclamide and tetracaine increase the osmotic resistance of the beta cells by affecting such ion transport.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects*; D002712:Chlorides / Q000378:metabolism*; D005905:Glyburide / Q000494:pharmacology; D007515:Islets of Langerhans / Q000502:physiology*; D051379:Mice; D008820:Mice, Obese; D009994:Osmolar Concentration; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D013748:Tetracaine / Q000494:pharmacology
D002712:Chlorides; D013748:Tetracaine; D010042:Ouabain; D011188:Potassium; D005905:Glyburide