Effects of nitric oxide on reactive oxygen species production and infarction size after brain reperfusion injury.
OBJECTIVE
Deleterious effects of strokes may be ameliorated when thrombolysis (i.e., with recombinant tissue plasminogen activator) restores circulation. However, reperfusion injury, mediated by oxygen free radicals (reactive oxygen species [ROS]), may limit the benefits of recombinant tissue plasminogen activator treatment. We hypothesized that, during reperfusion, exogenous nitric oxide (NO) would reduce stroke size by quenching ROS.


METHODS
To investigate this hypothesis, we used two in vivo ischemia-reperfusion models, i.e., autologous cerebral embolism in rabbits and filament middle cerebral artery occlusion in rats. Using these models, we measured ROS levels (rabbit model) and stroke volumes (rat model) in response to transient ischemia, with and without intracarotid administration of ultrafast NO donor proline NO (proliNO).


RESULTS
In the rabbit cerebral embolism model, intracarotid administration of proliNO (10(-6) mol/L) (n = 6) during reperfusion decreased free radical levels from 538 +/- 86 nmol/L in the vehicle-treated group (n = 7) to 186 +/- 31 nmol/L (2,3'-dihydroxybenzoic acid; P < 0.001) and from 521 +/- 86 nmol/L (n = 7) to 201 +/- 39 nmol/L (2,5'-dihydroxybenzoic acid; P < 0.002). In the rat middle cerebral artery occlusion model, intracarotid administration of proliNO (10(-5) mol/L) (n = 10) during reperfusion reduced the brain infarction volume from 256 +/- 48 mm3 in the vehicle-treated group (n = 8) to 187 +/- 41 mm3 (P < 0.005). In both experimental groups, intracarotid infusion of proliNO did not affect regional cerebral blood flow, mean arterial blood pressure, or brain and body temperatures.


CONCLUSIONS
The beneficial effects of early restoration of cerebral circulation after cerebral ischemia were enhanced by intracarotid infusion of proliNO, most likely because of ROS scavenging by NO. These findings suggest the possibility of preventive treatment of reperfusion injury using NO donors.
Pluta
R M
RM
Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-1414, USA. rysiek@ninds.nih.gov
Rak
R
R
Wink
D A
DA
Woodward
J J
JJ
Khaldi
A
A
Oldfield
E H
EH
Watson
J C
JC
D000818:Animals; D001921:Brain / Q000098:blood supply; D005260:Female; D020244:Infarction, Middle Cerebral Artery / Q000473:pathology / Q000503:physiopathology*; D007269:Injections, Intra-Arterial; D020766:Intracranial Embolism / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D009589:Nitrogen Oxides; D011392:Proline / Q000031:analogs & derivatives / Q000494:pharmacology*; D011817:Rabbits; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D015427:Reperfusion Injury / Q000473:pathology / Q000503:physiopathology*
D020030:Nitric Oxide Donors; D009589:Nitrogen Oxides; D017382:Reactive Oxygen Species; C102043:proline-nitric oxide; D009569:Nitric Oxide; D011392:Proline