title: Influence of tangential stress on mechanical responses to vasoactive agents in human saphenous vein with and without perivascular adipose tissue.
abstract: OBJECTIVE
  Improvement in short-term patency of vein grafts harvested with the surrounding tissue and no distention has been noted. The influence of transient tangential stress on mechanical function to vasoactive agents in isolated human saphenous veins stripped or with attached perivascular adipose tissue was assessed.
  
  
  METHODS
  Concentration-response curves to noradrenaline, 5-hydroxytryptamine, methylcholine, sodium nitroprusside and nicardipine were constructed for veins exposed to no, low (approximately 120 mmHg) or high (approximately 240 mmHg) tangential stress.
  
  
  RESULTS
  Tangential stress did not affect contractile effects of noradrenaline or relaxant effects of methylcholine and sodium nitroprusside. Regression analysis of the concentration-response curve to 5-hydroxytryptamine revealed a significant (P=0.042) increase in sensitivity in saphenous veins without perivascular adipose tissue exposed to no tangential stress, compared with veins with attached adipose tissue. Exposure to high stress significantly (P=0.024) increased the potency of 5-hydroxytryptamine in blood vessels without perivascular adipose tissue, as opposed to veins with adipose tissue. Relaxant responses to nicardipine in veins with perivascular adipose tissue were significantly (P=0.001) affected by exposure to low tangential stress compared with no or high tangential stress. A parallel comparison revealed that intact veins compared with those without perivascular adipose tissue exposed to low stress were significantly (P=0.020) more resistant to the relaxant effects of nicardipine.
  
  
  CONCLUSIONS
  The findings of the present report support the view that tangential stress has an impact on the actions of vasoactive agents, but this influence is variable and factor(s) released from perivascular adipose tissue may have a bearing on the observed effect.
authors.affiliation: Division of Basic Medical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St John's.
authors.forename: Carol Ann
authors.initials: CA
authors.lastname: Ford
authors.forename: Kam
authors.initials: K
authors.lastname: Mong
authors.forename: Reza
authors.initials: R
authors.lastname: Tabrizchi
mesh_terms: D000273:Adipose Tissue / Q000502:physiology; D000328:Adult; D000368:Aged; D002794:Choline / Q000031:analogs & derivatives / Q000494:pharmacology; D001026:Coronary Artery Bypass; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008082:Lipotropic Agents / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009599:Nitroprusside / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D012501:Saphenous Vein / Q000187:drug effects* / Q000502:physiology; D012701:Serotonin / Q000494:pharmacology; D018490:Serotonin Agents / Q000494:pharmacology; D013314:Stress, Mechanical; D014661:Vasoconstriction / Q000187:drug effects* / Q000502:physiology; D014662:Vasoconstrictor Agents / Q000494:pharmacology*; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D008082:Lipotropic Agents; D018490:Serotonin Agents; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; C017506:methylcholine; D009599:Nitroprusside; D012701:Serotonin; D002794:Choline; D009638:Norepinephrine