Bioflavonoid quercetin scavenges superoxide and increases nitric oxide concentration in ischaemia-reperfusion injury: an experimental study.
BACKGROUND
L-Arginine-depleted environments accompanying ischaemia-reperfusion enhance superoxide production, leading to the formation of reactive oxygen species and a concomitant reduction in basal nitric oxide levels. The bioflavonoid quercetin may prevent these undesirable effects by scavenging superoxide.


METHODS
Untreated rabbits were compared with those infused with quercetin (5 mg/kg for 2 min) during hindlimb ischaemia (2.5 h) and reperfusion (2 h). In both groups, nitric oxide concentration was measured (porphyrinic microsensor) in the femoral artery wall. Microvasculature changes (morphometry) and superoxide concentration (chemiluminescence) were measured intermittently in biopsies.


RESULTS
Approximately 6 min into the period of ischaemia a rapid increase in nitric oxide level from a mean(s.e.m.) basal level of 50(20) to 450(30) nmol/l was observed. In untreated animals, nitric oxide concentration dropped to an undetectable level (less than 1 nmol/l) during reperfusion. In quercetin-treated animals, the decrease in nitric oxide concentration was slower, such that substantial amounts (60(20) nmol/l) accumulated during reperfusion. In biopsies after ischaemia-reperfusion maximal calcium ionophore A23187-stimulated nitric oxide concentration increased (25-30 per cent) in the presence of quercetin, while the superoxide concentration decreased.


CONCLUSIONS
Quercetin treatment mollified ischaemia-reperfusion injury to skeletal muscle by scavenging destructive superoxide and enhancing the cytoprotective nitric oxide concentration.
Department of Vascular Surgery, University of Vienna, Medical School, Austria.
I
I
Huk
V
V
Brovkovych
J
J
Nanobash Vili
G
G
Weigel
C
C
Neumayer
L
L
Partyka
S
S
Patton
T
T
Malinski
D000818:Animals; D003250:Constriction; D005263:Femoral Artery / Q000378:metabolism; D006614:Hindlimb / Q000098:blood supply; D007511:Ischemia / Q000378:metabolism; D008297:Male; D008833:Microcirculation; D018482:Muscle, Skeletal / Q000098:blood supply; D009569:Nitric Oxide / Q000378:metabolism*; D011794:Quercetin / Q000627:therapeutic use*; D011817:Rabbits; D015427:Reperfusion Injury / Q000378:metabolism / Q000517:prevention & control*; D013481:Superoxides / Q000378:metabolism*
D013481:Superoxides; D009569:Nitric Oxide; D011794:Quercetin