The electrophysiological effects of tetraphenylphosphonium on vascular smooth muscle.
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.
Zhang
H
H
Department of Pharmacology and Clinical Pharmacology, St. George's Hospital Medical School, University of London, UK.
Bolton
T B
TB
Piekarska
A E
AE
McPherson
G A
GA
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
D006146:Guanidines; D009861:Onium Compounds; D009943:Organophosphorus Compounds; D015221:Potassium Channels; D014665:Vasodilator Agents; D019806:Cromakalim; D020110:Pinacidil; D000255:Adenosine Triphosphate; C013289:tetraphenylphosphonium