title: Insulinotropic action of glutamate is dependent on the inhibition of ATP-sensitive potassium channel activities in MIN 6 beta cells.
abstract: To investigate the cellular mechanism of insulinotropic effect of glutamate in pancreatic beta cells, we utilized patch-clamp technique to monitor directly the activities of ATP-sensitive potassium channels (K(ATP) channels). Dimethylglutamate (5mM), a membrane-permeable analog of glutamate, augmented the insulin release induced by the stimulatory concentrations of glucose (p<0.05-0.01). In the cell-attached configurations, dimethylglutamate reversibly and significantly suppressed the K(ATP) channel activities (p<0.01). On the other hand, no significant effect was observed when glutamate itself was applied to the inside-out patches, whereas the prompt and reversible suppression was recorded in the case of ATP (p<0.01). These results indicate that the insulinotropic action of glutamate in beta cells could be derived from the inhibition of K(ATP) channel activities, probably due to generation of messengers via intracellular metabolism such as ATP.
authors: Third Department of Internal Medicine, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 181-8611, Japan.
authors: Hidenori
authors: H
authors: Katsuta
authors: Sachihiko
authors: S
authors: Ozawa
authors: Tomonori
authors: T
authors: Ninomiya
authors: Tatsuhiro
authors: T
authors: Shimoyama
authors: Eisuke
authors: E
authors: Ito
authors: Toshiaki
authors: T
authors: Tanaka
authors: Shinya
authors: S
authors: Yamaguchi
authors: Hiroshi
authors: H
authors: Katahira
authors: Shinya
authors: S
authors: Nagamatsu
authors: Minoru
authors: M
authors: Horie
authors: Hitoshi
authors: H
authors: Ishida
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005947:Glucose / Q000737:chemistry; D018698:Glutamic Acid / Q000737:chemistry* / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism*; D008297:Male; D051379:Mice; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar
chemical_list: D007328:Insulin; D015221:Potassium Channels; D018698:Glutamic Acid; D000255:Adenosine Triphosphate; D005947:Glucose; D011188:Potassium