Potentiation by insulin and insulin-like growth factor-1 of glibenclamide-sensitive K+ currents in follicle-enclosed Xenopus oocytes.
Effects of insulin and IGF-1 (insulin-like growth factor-1) on K+ channel opener-induced/glibenclamide-sensitive K+ currents were studied using follicle-enclosed Xenopus oocytes. Both insulin (4 x 10(-9)-4 x 10(-6) M) and IGF-1 (4 x 10(-10)-4 x 10(-7) M) increased the cromakalim-induced K+ currents in a concentration-dependent manner. The current-facilitating effect of IGF-1 was about ten times as potent as that of insulin. Treatment of the oocyte with pertussis toxin (2 micrograms/ml) suppressed the current-potentiating effects of insulin and IGF-1 by about 60%. Although phenylarsine oxide (1-100 microM), a putative inhibitor of protein tyrosine phosphatase, also facilitated the K+ currents, the current enhancing effects were not affected by pertussis toxin. These results suggest that insulin and IGF-1 potentiate the glibenclamide-sensitive K+ current by activating IGF-1 receptor and that pertussis toxin-sensitive G-protein may be associated with these effects.
Sakuta
H
H
Department of Pharmacology, National Defense Medical College, Saitama, Japan.
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001152:Arsenicals / Q000494:pharmacology; D001578:Benzopyrans / Q000494:pharmacology; D019806:Cromakalim; D004357:Drug Synergism; D005260:Female; D005905:Glyburide / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism; D018408:Patch-Clamp Techniques; D037342:Pertussis Toxin; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D011758:Pyrroles / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D014982:Xenopus laevis
D000959:Antihypertensive Agents; D001152:Arsenicals; D001578:Benzopyrans; D007328:Insulin; D015221:Potassium Channels; D011758:Pyrroles; D010566:Virulence Factors, Bordetella; D019806:Cromakalim; C029341:oxophenylarsine; D007334:Insulin-Like Growth Factor I; D037342:Pertussis Toxin; C074338:Y 26763; D005905:Glyburide