Dihydropyridine action on voltage-dependent potassium channels expressed in Xenopus oocytes.
Dihydropyridines (DHPs) are well known for their effects on L-typed voltage-dependent Ca2+ channels, However, these drugs also affect other voltage-dependent ion channels, including Shaker K+ channels. We examined the effects of DHPs on the Shaker K+ channels expressed in Xenopus oocytes. Intracellular applications of DHPs quickly and reversibly induced apparent inactivation in the Shaker K+ mutant channels with disrupted N- and C-type inactivation. We found that DHPs interact with the open state of the channel as evidenced by the decreased mean open time. The DHPs effects are voltage-dependent, becoming more effective with hyperpolarization. A model which involves binding of two DHP molecules to the channel is consistent with the results obtained in our experiments.
Avdonin
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Department of Physiology and Biophysics, University of Iowa, Iowa City 52242, USA.
Shibata
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EF
Hoshi
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D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D004095:Dihydropyridines / Q000494:pharmacology*; D004558:Electric Stimulation; D004594:Electrophysiology; D015640:Ion Channel Gating / Q000187:drug effects; D008564:Membrane Potentials / Q000502:physiology; D051379:Mice; D009543:Nifedipine / Q000494:pharmacology; D009865:Oocytes / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D014981:Xenopus
D002121:Calcium Channel Blockers; D004095:Dihydropyridines; D015221:Potassium Channels; D009543:Nifedipine