title: Exercise reduces epicardial coronary artery wall stiffness: roles of cGMP and cAMP.
abstract: OBJECTIVE
  Exercise enhances the dilation of the epicardial coronary arteries by vasodilator drugs and blood flow. Our goal was to determine whether coronary artery elastic properties were affected by brief exercise training.
  
  
  METHODS
  Arterial pressure and left circumflex coronary artery diameter were measured in dogs. Venous bolus injections of acetylcholine 5 microg x kg(-1) (ACH) and nitroglycerin 25 microg x kg(-1) (NTG) or infusions of adenosine 0.5 microM/kg/min (ADO) were given. Fifteen-second coronary artery occlusions were performed. Dogs exercised 2 h x d(-1) for 7 d at 10.9 km x h(-1). Experiments were repeated. Pressure and coronary radius data were used to calculate vessel wall stress and incremental wall modulus, Einc.
  
  
  RESULTS
  Baseline Einc and radius were not changed by exercise. Before exercise Einc increased similarly from baseline for all vasodilators. After exercise, the increase in Einc with ADO was unchanged. However, the increase was attenuated during ACH, abolished with occlusion, and reversed with NTG despite enhanced dilation.
  
  
  CONCLUSIONS
  Data suggest that functional remodeling of epicardial arteries begins soon after starting exercise training, before changes in resting vessel diameter, is mediated by cGMP, and contributes to increased vascular dilation. Brief exercise training enhances the vasodilating capability and elastic properties of large coronary arteries.
authors.affiliation: Department of Physiology, New York Medical College, Valhalla 10595, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Stewart
authors.forename: X
authors.initials: X
authors.lastname: Xu
authors.forename: M
authors.initials: M
authors.lastname: Ochoa
authors.forename: T H
authors.initials: TH
authors.lastname: Hintze
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000241:Adenosine / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D003331:Coronary Vessels / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology*; D000242:Cyclic AMP / Q000502:physiology*; D006152:Cyclic GMP / Q000502:physiology*; D004285:Dogs; D004548:Elasticity; D005996:Nitroglycerin / Q000494:pharmacology; D010805:Physical Conditioning, Animal / Q000502:physiology*; D012044:Regression Analysis; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D014665:Vasodilator Agents; D000242:Cyclic AMP; D005996:Nitroglycerin; D006152:Cyclic GMP; D000241:Adenosine; D000109:Acetylcholine