title: The electrophysiological effects of tetraphenylphosphonium on vascular smooth muscle.
abstract: The effect of the lipophilic quaternary ion, tetraphenylphosphonium, on membrane potential of segments of rat small mesenteric artery and on the current in single voltage-clamped smooth muscle cells from rabbit portal vein was studied. In rat small mesenteric artery, tetraphenylphosphonium (1-30 microM) caused membrane depolarization of approximately 23 mV and decreased or abolished the hyperpolarization induced by the KATP channel opener, levcromakalim (0.1-3 microM). In rabbit portal vein K+ currents induced by levcromakalim (10 microM) or pinacidil (10 microM) were completely inhibited by tetraphenylphosphonium (IC50 0.5 microM). The results show that tetraphenylphosphonium antagonizes the KATP current induced by K+ channel openers in vascular smooth muscle possibly by acting on the KATP channel itself.
authors.affiliation: Department of Pharmacology and Clinical Pharmacology, St. George's Hospital Medical School, University of London, UK.
authors.forename: H
authors.initials: H
authors.lastname: Zhang
authors.forename: T B
authors.initials: TB
authors.lastname: Bolton
authors.forename: A E
authors.initials: AE
authors.lastname: Piekarska
authors.forename: G A
authors.initials: GA
authors.lastname: McPherson
mesh_terms: D000255:Adenosine Triphosphate / Q000502:physiology; D000818:Animals; D002478:Cells, Cultured; D019806:Cromakalim / Q000494:pharmacology; D004347:Drug Interactions; D004594:Electrophysiology; D006146:Guanidines / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D008638:Mesenteric Arteries / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology*; D009861:Onium Compounds / Q000494:pharmacology*; D009943:Organophosphorus Compounds / Q000494:pharmacology*; D020110:Pinacidil; D011169:Portal Vein / Q000187:drug effects / Q000502:physiology; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology; D011817:Rabbits; D051381:Rats; D011921:Rats, Inbred WKY; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D006146:Guanidines; D009861:Onium Compounds; D009943:Organophosphorus Compounds; D015221:Potassium Channels; D014665:Vasodilator Agents; D019806:Cromakalim; D020110:Pinacidil; D000255:Adenosine Triphosphate; C013289:tetraphenylphosphonium