title: Postconditioning fails to prevent radial artery endothelial dysfunction induced by ischemia and reperfusion: evidence from a human in vivo study.
abstract: Animal studies have shown that, as compared with unrestricted reperfusion, exposure to brief periods of controlled ischemia (postconditioning) at the end of a prolonged ischemia reduces the extent of tissue damage. We set out to test whether postconditioning can prevent endothelial dysfunction induced by ischemia and reperfusion in a human in vivo model. Ten healthy young non-smoking volunteers were enrolled in this cross-over, controlled, investigator-blinded study. Subjects were exposed to 15 min of forearm ischemia followed by either unrestricted reperfusion or postconditioning (3 periods of 20 s of ischemia separated by 10 s of reperfusion). Endothelium-dependent flow-mediated dilation (FMD) was measured at the level of the radial artery before and after ischemia (with or without postconditioning). Forearm ischemia blunted FMD in both study visits (unrestricted reperfusion visit: before ischemia, 7.7% +/- 1.3%; after ischemia, 2.5% +/- 1.4%; and postconditioning visit: before, 7.3% +/- 1.2%; after, 2.6 +/- 1.6%; P < 0.05 for both, P = not significant (NS) between visits). In contrast with data from animal studies, postconditioning (20 s ischemia-- 10 s reperfusion repeated 3 times) does not limit post-ischemic endothelial dysfunction in this human in vivo model. Further human studies are necessary to evaluate other reperfusion protocols in an attempt to limit post-ischemic tissue damage.
authors.affiliation: Department of Internal, Cardiovascular and Geriatric Medicine, Azienda Ospedaliera Universitaria Senese, University of Siena, Italy.
authors.forename: Saverio
authors.initials: S
authors.lastname: Dragoni
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Di Stolfo
authors.forename: Silvia
authors.initials: S
authors.lastname: Sicuro
authors.forename: Monica
authors.initials: M
authors.lastname: Lisi
authors.forename: John D
authors.initials: JD
authors.lastname: Parker
authors.forename: Sandro
authors.initials: S
authors.lastname: Forconi
authors.forename: Tommaso
authors.initials: T
authors.lastname: Gori
mesh_terms: D000328:Adult; D001132:Arm / Q000098:blood supply; D001916:Brachial Artery / Q000502:physiology; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004730:Endothelium, Vascular / Q000293:injuries*; D006801:Humans; D007511:Ischemia / Q000628:therapy*; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods*; D008297:Male; D008875:Middle Aged; D017534:Radial Artery / Q000033:anatomy & histology / Q000293:injuries*; D012039:Regional Blood Flow; D015424:Reperfusion / Q000009:adverse effects*; D015427:Reperfusion Injury / Q000517:prevention & control*; D017211:Treatment Failure