OXYGEN RADICALS DO NOT PLAY A ROLE IN ARTERIOLAR DILATION DURING CORTICAL SPREADING DEPRESSION

This study examined the role of oxygen radicals in pial arteriolar cha nges during cortical spreading depression (CSD). (CSD) was induced by microinjection of 5% KCl in anesthetized adult rabbits. Pial diameter was measured with a closed cranial window and intravital microscopy. D uring control CSD (n=12), the dilation amplitude and area were 55 +/- 14% and 693 +/- 69 mm(2) (baseline=76 +/- 14 mu m), respectively. Oxyg en radical scavengers, superoxide dismutase (SOD; 105 U/ml, topical ap plication; n=5) or oxypurinol (50 mg/kg i.v.; n=7), did not alter the dilation amplitude and area or change onset latency during CSD. Furthe r, SOD and oxypurinol did not prevent N-G-nitro-L-arginine from attenu ating arteriolar dilation during CSD (n=12). We conclude that oxygen r adicals do not play a role in the transient dilation of cerebral arter ioles during CSD.