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

Background and Purpose We attempted to determine whether N-omega-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 mg/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; GNAME-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.