title: Comparative effects of tolazoline and nitroprusside on human isolated radial artery.
abstract: BACKGROUND
  The radial artery is increasingly being used in coronary revascularization as an alternative conduit to a saphenous vein graft. Its perfect endothelial capacity provides a high patency rate comparable with the internal mammary artery (IMA). However, its spastic characteristics cause difficulties during its intraoperative preparation and may lead to early postoperative graft failure. Thus, treatment and/or prevention of radial artery spasm with an effective vasodilator agent is essential for its longevity. Endogenous vasoconstrictors, including noradrenaline, endothelin-1, and thromboxane A2, are likely to play a role in the pathogenesis of graft spasm. In the present study, we evaluated the vasorelaxant effect of tolazoline, a nonselective alpha-adrenoceptor blocker, against the contractions induced by various spasmogenic agents in an isolated human radial artery.
  
  
  METHODS
  Tolazoline (10(-9)-10(-4) M) or sodium nitroprusside (SNP, 10(-9)-10(-4) M) were cumulatively applied on radial artery rings precontracted submaximally with noradrenaline, endothelin-1, thromboxane analogue, U46619, or potassium chloride. In addition, some rings were pretreated with tolazoline (4 x 10(-6) M) for 30 minutes and the contractile response curve to noradrenaline was assessed in its presence.
  
  
  RESULTS
  Tolazoline effectively reversed noradrenaline-induced contractions in the radial artery, whereas it failed to produce remarkable relaxations on rings contracted with other spasmogenic agents, while SNP overcame the contractions induced by all spasmogens to a similar extent. In addition, brief pretreatment of radial artery rings with tolazoline significantly inhibited the contractions to noradrenaline.
  
  
  CONCLUSIONS
  Tolazoline is not as broadly effective as SNP against all spasmogens investigated; however, it may be effective in counteracting alpha-adrenoceptor-mediated vasospasm in human radial arteries.
authors.affiliation: Department of Cardiovascular Surgery, Siyami Ersek Thoracic and Cardiovascular Surgery Education and Research Hospital, Istanbul, Turkey.
authors.forename: Onder
authors.initials: O
authors.lastname: Teskin
authors.forename: B Sönmez
authors.initials: BS
authors.lastname: Uydeş-Dogan
authors.forename: Yavuz
authors.initials: Y
authors.lastname: Enç
authors.forename: F Ilkay
authors.initials: FI
authors.lastname: Alp
authors.forename: Deniz
authors.initials: D
authors.lastname: Kaleli
authors.forename: Süheyla
authors.initials: S
authors.lastname: Keser
authors.forename: Taner
authors.initials: T
authors.lastname: Iyigün
authors.forename: Fuat
authors.initials: F
authors.lastname: Bilgen
authors.forename: Sabri
authors.initials: S
authors.lastname: Dagsali
authors.forename: Osman
authors.initials: O
authors.lastname: Ozdemir
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D004353:Drug Evaluation, Preclinical; D019332:Endothelin-1 / Q000494:pharmacology; D006801:Humans; D009599:Nitroprusside / Q000494:pharmacology*; D009638:Norepinephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D017534:Radial Artery / Q000187:drug effects*; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000502:physiology; D014043:Tolazoline / Q000494:pharmacology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D019332:Endothelin-1; D011942:Receptors, Adrenergic, alpha; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D009599:Nitroprusside; D011189:Potassium Chloride; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D014043:Tolazoline; D009638:Norepinephrine