title: Vasoconstrictor responses to vasopressor agents in human pulmonary and radial arteries: an in vitro study.
abstract: BACKGROUND
  Vasopressor drugs, commonly used to treat systemic hypotension and maintain organ perfusion, may also induce regional vasoconstriction in specialized vascular beds such as the lung. An increase in pulmonary vascular tone may adversely affect patients with pulmonary hypertension or right heart failure. While sympathomimetics constrict pulmonary vessels, and vasopressin does not, a direct comparison between these drugs has not been made. This study investigated the effects of clinically used vasopressor agents on human isolated pulmonary and radial arteries.
  
  
  METHODS
  Isolated pulmonary and radial artery ring segments, mounted in organ baths, were used to study the contractile responses of each vasopressor agent. Concentration-response curves to norepinephrine, phenylephrine, metaraminol, and vasopressin were constructed.
  
  
  RESULTS
  The sympathomimetics norepinephrine, phenylephrine, and metaraminol caused concentration-dependent vasoconstriction in the radial (pEC50: 6.99 ± 0.06, 6.14 ± 0.09, and 5.56 ± 0.07, respectively, n = 4 to 5) and pulmonary arteries (pEC50: 6.86 ± 0.11, 5.94 ± 0.05 and 5.56 ± 0.09, respectively, n = 3 to 4). Vasopressin was a potent vasoconstrictor of the radial artery (pEC50 9.13 ± 0.20, n = 3), whereas in the pulmonary artery, it had no significant effect.
  
  
  CONCLUSIONS
  Sympathomimetic-based vasopressor agents constrict both human radial and pulmonary arteries with similar potency in each. In contrast, vasopressin, although a potent vasoconstrictor of radial vessels, had no effect on pulmonary vascular tone. These findings provide some support for the use of vasopressin in patients with pulmonary hypertension.
authors.affiliation: From the Cardiovascular Therapeutics Unit, Department of Pharmacology and Therapeutics, The University of Melbourne, Victoria, Australia (D.A.C., R.J.A.H., C.E.W., J.A.A., P.F.S.) and Department of Anaesthesia and Pain Medicine, Royal Melbourne Hospital, Parkville, Australia (D.A.C., P.F.S.).
authors.forename: Dale A
authors.initials: DA
authors.lastname: Currigan
authors.forename: Richard J A
authors.initials: RJ
authors.lastname: Hughes
authors.forename: Christine E
authors.initials: CE
authors.lastname: Wright
authors.forename: James A
authors.initials: JA
authors.lastname: Angus
authors.forename: Paul F
authors.initials: PF
authors.lastname: Soeding
mesh_terms: D001127:Arginine Vasopressin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D066298:In Vitro Techniques; D011651:Pulmonary Artery / Q000187:drug effects*; D017534:Radial Artery / Q000187:drug effects*; D013566:Sympathomimetics / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology*; D014664:Vasodilation / Q000187:drug effects
chemical_list: D013566:Sympathomimetics; D014662:Vasoconstrictor Agents; D001127:Arginine Vasopressin