Somatostatin activates glibenclamide-sensitive and ATP-regulated K+ channels in insulinoma cells via a G-protein.
Somatostatin, an hyperglycemia-inducing hormone, was studied in rat insulinoma (RINm5F) cells using 86Rb+ efflux techniques. 86Rb+ efflux is stimulated by somatostatin in a dose-dependent manner. The half-maximum value of activation is 0.7 nM. Somatostatin-induced 86Rb+ efflux is abolished by the hypoglycemia-inducing sulfonylurea, glibenclamide, a known blocker of ATP-regulated K+ channels. Somatostatin activation is prevented by pretreatment of insulinoma cells with pertussis toxin. 86Rb+ efflux studies show that somatostatin activates an ATP-dependent K+ channel.
Fosset
M
M
Centre de Biochimie, Centre National de la Recherche Scientifique, Nice, France.
Schmid-Antomarchi
H
H
de Weille
J R
JR
Lazdunski
M
M
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D003847:Deoxyglucose / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000502:physiology*; D005905:Glyburide / Q000494:pharmacology*; D007340:Insulinoma / Q000378:metabolism; D009840:Oligomycins / Q000494:pharmacology; D010190:Pancreatic Neoplasms / Q000378:metabolism; D037342:Pertussis Toxin; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D012414:Rubidium Radioisotopes / Q000378:metabolism; D013004:Somatostatin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D009840:Oligomycins; D015221:Potassium Channels; D012414:Rubidium Radioisotopes; D010566:Virulence Factors, Bordetella; D013004:Somatostatin; D000255:Adenosine Triphosphate; D003847:Deoxyglucose; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D005905:Glyburide