title: Ionic requirements of the endothelin response in aorta and portal vein.
abstract: The vasoconstrictor responses of isolated rat portal vein and aorta to synthetically prepared endothelin are investigated. Both preparations respond to 10(-9) M levels of the peptide although the aortic response is more sustained than that of the portal vein. Endothelin-evoked contractions, unlike those evoked by scorpion alpha-toxins (which are homologous to endothelin) or by veratridine, are insensitive to tetrodotoxin or to the removal of sodium ions from the tissue-bathing medium. Contractile responses to endothelin may still be observed in high-potassium depolarizing medium and are not dependent on the presence of extracellular chloride; however, the responses are dependent on the presence of extracellular calcium and are blocked by nitrendipine, nifedipine, or nickel. Endothelin-evoked uptake of 45Ca into aortic tissue is also independent of extracellular sodium or potassium and is blocked by nifedipine. These data strongly suggest that endothelin acts at a site closely coupled to the calcium channel and that depolarization by sodium influx through voltage-dependent channels is not involved in endothelin-induced vasoconstriction.
authors.affiliation: Division of Biomedical Sciences, King's College, University of London, England.
authors.forename: R
authors.initials: R
authors.lastname: Borges
authors.forename: D V
authors.initials: DV
authors.lastname: Carter
authors.forename: H
authors.initials: H
authors.lastname: von Grafenstein
authors.forename: J
authors.initials: J
authors.lastname: Halliday
authors.forename: D E
authors.initials: DE
authors.lastname: Knight
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects*; D015220:Calcium Channels / Q000502:physiology; D016232:Endothelins; D004730:Endothelium, Vascular / Q000378:metabolism; D007477:Ions; D008297:Male; D008955:Models, Cardiovascular; D010455:Peptides / Q000494:pharmacology*; D010477:Perfusion; D010656:Phenylephrine / Q000494:pharmacology; D011169:Portal Vein / Q000187:drug effects*; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012079:Renal Circulation / Q000187:drug effects; D012964:Sodium / Q000494:pharmacology; D014661:Vasoconstriction
chemical_list: D015220:Calcium Channels; D016232:Endothelins; D007477:Ions; D010455:Peptides; D010656:Phenylephrine; D012964:Sodium; D011188:Potassium