Activation by KRN2391 and nicorandil of glibenclamide-sensitive K+ channels in Xenopus oocytes.
KRN2391 (N-cyano-N'-(2-nitroxyethyl)-3-pyridine-carboximidamide methanesulfonate) and nicorandil, a new class of K+ channel openers, each with an NO2 moiety, induced outward K+ currents in follicle-enclosed Xenopus oocytes. These K+ currents were suppressed concentration-dependently and reversibly by glibenclamide, phentolamine and trifluoperazine, all known to inhibit ATP-sensitive K+ channels. The nicorandil-induced K+ current was virtually abolished by defolliculation of oocytes, while the KRN2391 response was little affected by defolliculation. These results suggest that Xenopus oocyte has at least two types of glibenclamide-sensitive K+ channels, one is selectively sensitive to KRN2391 and is probably localized in the oocyte, and the other is sensitive to nicorandil and distributed in the follicle cells surrounding an oocyte.
Sakuta
H
H
Department of Pharmacology, National Defense Medical College, Saitama, Japan.
Okamoto
K
K
D000818:Animals; D001578:Benzopyrans / Q000494:pharmacology; D019806:Cromakalim; D004594:Electrophysiology; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D005905:Glyburide / Q000494:pharmacology; D009536:Niacinamide / Q000031:analogs & derivatives* / Q000494:pharmacology; D020108:Nicorandil; D009865:Oocytes / Q000187:drug effects* / Q000378:metabolism; D010646:Phentolamine / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects*; D011725:Pyridines / Q000494:pharmacology*; D011758:Pyrroles / Q000494:pharmacology; D014268:Trifluoperazine / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology*; D014982:Xenopus laevis
D001578:Benzopyrans; D015221:Potassium Channels; D011725:Pyridines; D011758:Pyrroles; D014665:Vasodilator Agents; D019806:Cromakalim; C070492:N-cyano-N'-(2-nitroxyethyl)-3-pyridinecarboximidamide methanesulfonate; D014268:Trifluoperazine; D009536:Niacinamide; D020108:Nicorandil; D005905:Glyburide; D004837:Epinephrine; D010646:Phentolamine