Inhibition of cromakalim-activated K+ current by ethanol in follicle-enclosed Xenopus oocytes.
Ethanol has been reported to modulate arterial dilation and insulin secretion. ATP-inhibited K+ channels (K(ATP)) are reported to have regulatory roles during these events. In the present study, the effect of ethanol on K+ currents activated by the K(ATP) channel opener cromakalim was investigated in follicular cells of Xenopus oocytes. The results indicate that ethanol in the concentration range of 10-300 mM (approximately 0.06%-2% v/v) reversibly inhibits the cromakalim-induced K+ currents. The 50% of maximal ethanol effect was obtained at 53 mM. Inhibition of cromakalim-activated K+ current by ethanol was non-competitive. In oocytes treated with the Ca2+-chelator BAPTA, inhibition of cromakalim-induced K+ currents by ethanol was not altered, suggesting that Ca2+-activated second messenger pathways were not involved in the actions of ethanol. Similarly, currents activated by 8-Br-cAMP were also inhibited by ethanol, but the ethanol inhibition of 8-Br-cAMP-activated currents was significantly less than inhibition of cromakalim-activated currents by ethanol. These results indicate that cromakalim-activated K+ currents in follicular cells of Xenopus oocytes were modulated by ethanol.
Oz
Murat
M
NIDA/IRP Cellular Neurobiology Branch, 5500 Nathan Shock Drive, Baltimore, MD 21224, USA. moz@intra.nida.nih.gov
Tchugunova
Yulia
Y
Dinc
Meral
M
D000818:Animals; D019806:Cromakalim / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology*; D005260:Female; D009865:Oocytes / Q000187:drug effects* / Q000502:physiology; D006080:Ovarian Follicle / Q000187:drug effects* / Q000502:physiology; D026902:Potassium Channel Blockers / Q000494:pharmacology*; D015221:Potassium Channels / Q000378:metabolism*; D014982:Xenopus laevis
D026902:Potassium Channel Blockers; D015221:Potassium Channels; D019806:Cromakalim; D000431:Ethanol; D004533:Egtazic Acid; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid