title: Comparison of U46619-, endothelin-1- or phenylephrine-induced changes in cellular Ca2+ profiles and Ca2+ sensitisation of constriction of pressurised rat resistance arteries.
abstract: 1. In pressurised rat mesenteric small arteries (50 mmHg), we examined the effects of stimulation with U46619, endothelin-1 (ET-1) or phenylephrine (PE) on changes in vessel diameter, global [Ca(2+)](i), individual smooth muscle cell [Ca(2+)](i) and Ca(2+)-sensitisation of contraction. 2. U46619 or ET-1 gave tonic diameter reductions, whereas PE-stimulated vessels gave tonic contractions or initial vasoconstrictions followed by diameter oscillations. Global [Ca(2+)](i) changes were transient for each agonist, with tonic constrictions being accompanied by maintained submaximal global [Ca(2+)](i) levels. 3. U46619, ET-1 or PE tonic constrictions were accompanied by apparently asynchronous [Ca(2+)](i) waves in individual smooth muscle cells of the vessel wall, as examined by confocal fluorescent microscopy. In vessels exhibiting vasomotion to PE, some apparent synchrony of activation of individual cells was evident; however, this was incomplete with many cells responding out of phase with their neighbours. 4. In alpha-toxin-permeabilised preparations, agonist-induced Ca(2+)-sensitisation of constriction at submaximal Ca(2+) (pCa6.7) in the presence of GTP was greater with U46619 or ET than PE. 5. We conclude that, in pressurised mesenteric arteries, (i) a general feature of receptor-coupled constriction is the generation of periodic smooth muscle [Ca(2+)](i) waves; (ii) complete synchrony of Ca(2+) oscillations between smooth muscle cells is not a prerequisite for receptor-coupled vasomotion; (iii) varied Ca(2+)-sensitising actions of agonists may partly determine tonic or phasic vessel responses to different stimuli.
authors.affiliation: Smooth Muscle Physiology Group, Cardiovascular Research, University of Manchester, Manchester.
authors.forename: Linda
authors.initials: L
authors.lastname: Shaw
authors.forename: Stephen
authors.initials: S
authors.lastname: O'Neill
authors.forename: Carolyn J P
authors.initials: CJ
authors.lastname: Jones
authors.forename: Clare
authors.initials: C
authors.lastname: Austin
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Taggart
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology*; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects*; D019332:Endothelin-1 / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects / Q000502:physiology; D009119:Muscle Contraction / Q000187:drug effects; D009129:Muscle Tonus / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects*; D010656:Phenylephrine / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D017466:Receptors, Endothelin / Q000819:agonists; D017482:Receptors, Thromboxane / Q000819:agonists; D010738:Type C Phospholipases / Q000494:pharmacology; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
chemical_list: D000316:Adrenergic alpha-Agonists; D019332:Endothelin-1; D017466:Receptors, Endothelin; D017482:Receptors, Thromboxane; D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D010738:Type C Phospholipases; D011188:Potassium; D002118:Calcium