Modification by cGMP of glibenclamide-sensitive K+ currents in Xenopus oocytes.
Effects of sodium nitroprusside, 8-bromo cGMP and methylene blue on the glibenclamide-sensitive K+ current evoked by K+ channel openers in Xenopus oocytes were studied. Sodium nitroprusside (0.1-1 mM, an activator of guanylate cyclase) enhanced by 20-50% the K+ currents induced by KRN2391, nicorandil and cromakalim (K+ channel openers). 8-Bromo cGMP (1 mM) also increased the K+ current by 40-60%. Methylene blue (10 microM, an inhibitor of guanylate cyclase) irreversibly blocked the K+ current by about 20-30%. These results suggest that the activation of glibenclamide-sensitive K+ channels by K+ channel openers is modulated either positively or negatively by intracellular cGMP in oocytes.
Department of Pharmacology, National Defense Medical College, Saitama, Japan.
H
H
Sakuta
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K
Okamoto
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Y
Watanabe
D000818:Animals; D001578:Benzopyrans / Q000494:pharmacology; D019806:Cromakalim; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000494:pharmacology / Q000502:physiology*; D005260:Female; D005905:Glyburide / Q000494:pharmacology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D008751:Methylene Blue / Q000494:pharmacology; D009536:Niacinamide / Q000031:analogs & derivatives / Q000494:pharmacology; D020108:Nicorandil; D009599:Nitroprusside / Q000494:pharmacology; D009865:Oocytes / Q000187:drug effects* / Q000378:metabolism; D015221:Potassium Channels / Q000187:drug effects*; D011725:Pyridines / Q000494:pharmacology; D011758:Pyrroles / Q000494:pharmacology; D014982:Xenopus laevis
D001578:Benzopyrans; D015221:Potassium Channels; D011725:Pyridines; D011758:Pyrroles; D019806:Cromakalim; C070492:N-cyano-N'-(2-nitroxyethyl)-3-pyridinecarboximidamide methanesulfonate; D009599:Nitroprusside; D009536:Niacinamide; D020108:Nicorandil; C016276:8-bromocyclic GMP; D006152:Cyclic GMP; D005905:Glyburide; D008751:Methylene Blue