Neither L-arginine nor L-NAME affects neurological outcome after global ischemia in cats

Background and Purpose: We attempted to determine whether N(ω)-nitro- L-arginine methyl ester (L-NAME) would improve neurological outcome and whether L-arginine (L-ARG) would worsen neurological outcome after transient global ischemia. Methods: Halothane-anesthetized cats (n=6 for each group) were treated with intravenous saline, L-NAME (5 mg/kg or 10 mg/kg), or L- arginine (300 kg) 30 minutes before 10 minutes of ischemia (temporary ligation of the left subclavian and brachiocephalic arteries with hemorrhagic hypotension to 50 mm Hg). At 30 minutes of reperfusion, cats in the L-ARG group were administered an additional 300 mg/kg dose of intravenous L- arginine. Results: Time (mean±SE) to isoelectric electroencephalography was similar among groups (saline, 26±11 seconds; L-NAME-5, 15±4 seconds; L- NAME-10, 36±27 seconds; and L-ARG, 22±7 seconds). At 72 hours, reperfusion pathological injury was severe and neurological deficit score (mean, range) was similar among groups (saline, 38 [11 to 70]; L-NAME-5, 52 [40 to 73]; L- NAME-10, 47 [23 to 70]; and L-ARG, 40 [0 to 79]). Conclusions: Nitric oxide is not important in the mechanism of brain injury after global ischemia in cats.