title: Tezosentan, a combined parenteral endothelin receptor antagonist, produces pulmonary vasodilation in lambs with acute and chronic pulmonary hypertension.
abstract: OBJECTIVE
  To investigate the hemodynamic effects of tezosentan in the intact lamb both at rest and during acute and chronic pulmonary hypertension.
  
  
  METHODS
  Prospective, randomized experimental study.
  
  
  METHODS
  University-based research laboratory.
  
  
  METHODS
  Lambs with and without pulmonary hypertension.
  
  
  METHODS
  Six newborn lambs were instrumented to measure vascular pressures and left pulmonary blood flow. The hemodynamic effects of tezosentan (0.5, 1.0, 5.0 mg/kg, intravenously) were studied at rest and during U46619-induced pulmonary hypertension. Following in utero placement of an aortopulmonary vascular graft, nine additional lambs with increased pulmonary blood flow and chronic pulmonary hypertension (shunt) were also studied at 1 wk (n = 5) and 8 wks (n = 4) of age.
  
  
  RESULTS
  At rest, tezosentan had no significant effect on any of the variables. During acute U46619-induced pulmonary hypertension, tezosentan caused a dose-dependent decrease in pulmonary arterial pressure (from 5.9% +/- 4.7 to 16.0% +/- 10.7; p < .05) and pulmonary vascular resistance (from 6.2% +/- 8.0 to 21% +/- 8.8; p < .05). Mean systemic arterial pressure was unchanged. In 1- and 8-wk-old shunt lambs with increased pulmonary blood flow, tezosentan (1 mg/kg) produced potent nonselective pulmonary vasodilation.
  
  
  CONCLUSIONS
  Tezosentan, a combined endothelin receptor antagonist optimized for parenteral use, induces potent selective pulmonary vasodilation during acute U46619-induced pulmonary hypertension and potent nonselective vasodilation in chronic pulmonary hypertension secondary to increased pulmonary blood flow. In general, the hemodynamic effects of bolus doses of tezosentan occurred within 60 secs of administration and lasted approximately 5-10 mins. The hemodynamic profile of intravenous tezosentan may make it a useful adjunct therapy for acute pulmonary hypertensive disorders and warrants further study.
authors.affiliation: Department of Pediatrics, University of California-San Francisco, San Francisco, CA 94143-0106, USA.
authors.forename: Robert K
authors.initials: RK
authors.lastname: Fitzgerald
authors.forename: Peter
authors.initials: P
authors.lastname: Oishi
authors.forename: Boaz
authors.initials: B
authors.lastname: Ovadia
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Ross
authors.forename: Olaf
authors.initials: O
authors.lastname: Reinhartz
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Johengen
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Fineman
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000208:Acute Disease; D000818:Animals; D000831:Animals, Newborn; D002908:Chronic Disease; D004305:Dose-Response Relationship, Drug; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1 / Q000494:pharmacology; D016232:Endothelins / Q000494:pharmacology; D006976:Hypertension, Pulmonary / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology; D007269:Injections, Intra-Arterial; D011652:Pulmonary Circulation / Q000187:drug effects; D011725:Pyridines / Q000494:pharmacology / Q000627:therapeutic use*; D011897:Random Allocation; D012756:Sheep; D013777:Tetrazoles / Q000494:pharmacology / Q000627:therapeutic use*; D014662:Vasoconstrictor Agents; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1; D016232:Endothelins; D011725:Pyridines; D013777:Tetrazoles; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; C061779:endothelin 1, Ala(1,3,11,15)-; C120582:tezosentan; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid