H2O2 induced hyperpolarization of pancreatic B-cells.
Conventional electrophysiology and the whole-cell patch-clamp technique have been applied to elucidate the effects of H2O2 on pancreatic B-cells of the mouse. In these cells, addition of 15 mmol/l glucose leads to depolarization and oscillation of the cell membrane potential. Subsequent addition of H2O2 (1 mmol/l) in the presence of glucose was followed by a marked and rapid hyperpolarization of the cell membrane with suppression of the electrical activity. Accordingly, in slow whole-cell patch-clamp experiments (with nystatin in the pipette solution) H2O2 induced a marked increase of cell membrane conductance. Tolbutamide, a blocker of K+ ATP channels, only partially blocked the effect of H2O2 even at high concentrations. The H2O2-induced, tolbutamide-insensitive current component, however, was largely abolished by a high concentration of TEA+ (80 mmol/l) or BaCl2 (10 mmol/l). It is concluded that in B-cells H2O2 stimulates a K+ current and that this effect leads to marked hyperpolarization and reversal of glucose-induced oscillations of cell membrane potential.
Krippeit-Drews
P
P
Department of Physiology, University of Tübingen, Germany.
Lang
F
F
Häussinger
D
D
Drews
G
G
D000818:Animals; D017609:Barium Compounds / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects; D002712:Chlorides / Q000494:pharmacology; D004594:Electrophysiology; D005260:Female; D005947:Glucose / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D066298:In Vitro Techniques; D007515:Islets of Langerhans / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D014044:Tolbutamide / Q000494:pharmacology
D017609:Barium Compounds; D002712:Chlorides; D015221:Potassium Channels; D000644:Quaternary Ammonium Compounds; C024986:barium chloride; D014044:Tolbutamide; D006861:Hydrogen Peroxide; D005947:Glucose