title: Increased tissue angiotensin-converting enzyme activity impairs bradykinin-induced dilation of coronary arterioles in obesity.
abstract: BACKGROUND
  Bradykinin (BK) is a key mediator regulating coronary blood flow. It is degraded by angiotensin-converting enzyme (ACE), but what is unknown is whether enhanced tissue ACE activity interferes with BK-induced coronary vasodilation in obesity.
  
  
  RESULTS
  Coronary arterioles (~100 μm) were isolated from rats on a normal or high-fat diet (HFD) and from lean or obese patients undergoing heart surgery (n=74). We found that BK-induced dilation was diminished in the coronary arterioles of HFD rats, when compared with controls. When administered in vitro, the ACE inhibitor, captopril, restored the coronary dilation response to BK in HFD rats, but did not affect control responses. Abundant ACE expression was detected in coronary endothelium, which was associated with increased ACE activity in HFD arterioles, as measured by increased response to the ACE substrate, angiotensin I. Moreover, we found that in the coronary arterioles of obese patients, BK-induced dilation was augmented by in vitro captopril administration. Correspondingly, ACE activity was increased in the coronary arterioles of obese patients when compared with the non-obese. Logistic regression analysis revealed that obese patients taking ACE inhibitors prior to surgery exhibited an enhanced dilation response to BK.
  
  
  CONCLUSIONS
  We demonstrated augmented tissue ACE activity in the coronary arterioles of obese subjects, which leads to reduced coronary dilation response to BK. We provide a rationale for ACE inhibitor therapy in obese patients to improve dilatation of coronary microvessels.
authors.affiliation: Vascular Biology Center, Georgia Health Sciences University, Augusta, GA 30912, USA.
authors.forename: Attila
authors.initials: A
authors.lastname: Feher
authors.forename: James
authors.initials: J
authors.lastname: Cassuto
authors.forename: Andras
authors.initials: A
authors.lastname: Szabo
authors.forename: Vijay
authors.initials: V
authors.lastname: Patel
authors.forename: M
authors.initials: M
authors.lastname: Vinayak Kamath
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Bagi
mesh_terms: D000368:Aged; D000803:Angiotensin I / Q000378:metabolism; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000008:administration & dosage; D000818:Animals; D001160:Arterioles / Q000201:enzymology / Q000503:physiopathology; D001920:Bradykinin / Q000378:metabolism / Q000494:pharmacology*; D002216:Captopril / Q000008:administration & dosage; D003331:Coronary Vessels / Q000201:enzymology / Q000502:physiology; D004730:Endothelium, Vascular / Q000201:enzymology / Q000503:physiopathology; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D014665:Vasodilator Agents; D000803:Angiotensin I; D002216:Captopril; C488034:ACE protein, human; D007703:Peptidyl-Dipeptidase A; D001920:Bradykinin