title: 3',4'-Dihydroxyflavonol improves post-ischaemic coronary endothelial function following 7days reperfusion in sheep.
abstract: 3',4'-dihydroxyflavonol (DiOHF) is a potent antioxidant that reduces infarct size following myocardial ischaemia-reperfusion. Since oxidative stress induced by myocardial ischaemia-reperfusion impairs endothelium-dependent vasodilatation, we investigated whether DiOHF preserved coronary endothelial function following ischemia-reperfusion. One week after surgery conscious, instrumented sheep were subjected to 1h of myocardial ischaemia followed by 7 days reperfusion. Immediately before reperfusion, sheep were injected with DiOHF (2mg/kg iv, n=4) or vehicle (dimethyl sulphoxide, n=4). Coronary vascular responses to the endothelium-dependent vasodilator acetylcholine (ACh, 0.05-10.0 microg/kg/min iv), sodium nitroprusside and phenylephrine were determined. After ischaemia-reperfusion, dP/dt(max) decreased from 1511+/-93 to 1094+/-53 mmHg/s, P<0.05) at 24h in the vehicle group, but by 7 days had returned towards baseline (1347+/-91 mmHg/s). DiOHF prevented the fall in dP/dt(max). Coronary conductance (CC) was increased (+34+/-4%) by 10 microg/kg ACh given before ischaemia, but this vasodilatation was significantly reduced after 24h and 7 days of reperfusion (+7+/-2%, +15+/-2%, respectively, both P<0.05). DiOHF partially preserved the coronary vasodilator response to ACh after 24h reperfusion (basal 37+/-7%, 24h 18+/-5%), and after 7 days reperfusion the response had recovered (31+/-7%). DiOHF significantly decreased infarct size, expressed as a percentage of area-at-risk, by 40% after 7 days reperfusion (vehicle 80+/-7%, DiOHF 46+/-11%, P<0.05). A single administration of DiOHF, during ischaemia and just prior to reperfusion, reduced infarct size, preserved ventricular contractility and caused a sustained protection against coronary endothelial dysfunction, with all these beneficial actions being preserved for 7 days reperfusion.
authors.affiliation: Howard Florey Institute, University of Melbourne, Victoria 3010, Australia.
authors.forename: Sheng
authors.initials: S
authors.lastname: Wang
authors.forename: Colleen J
authors.initials: CJ
authors.lastname: Thomas
authors.forename: Greg J
authors.initials: GJ
authors.lastname: Dusting
authors.forename: Owen L
authors.initials: OL
authors.lastname: Woodman
authors.forename: Clive N
authors.initials: CN
authors.lastname: May
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology / Q000627:therapeutic use*; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000502:physiology* / Q000503:physiopathology; D044948:Flavonols / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology / Q000627:therapeutic use*; D017202:Myocardial Ischemia / Q000188:drug therapy* / Q000503:physiopathology; D015425:Myocardial Reperfusion; D009599:Nitroprusside / Q000378:metabolism; D010656:Phenylephrine / Q000378:metabolism; D012756:Sheep; D013997:Time Factors; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
chemical_list: D000975:Antioxidants; D044948:Flavonols; D009599:Nitroprusside; D010656:Phenylephrine; D000109:Acetylcholine; C529890:3',4'-dihydroxyflavonol