Nitric Oxide Synthase (NOS) Inhibition and the Delayed Fall in Oxidised Cytochrome Oxidase After Cerebral Ischaemia in Fetal Sheep. 158

Background: Cerebral ischaemia (CI) leads to a delayed fall in oxidised cytochrome oxidase ([CytO₂]). We tested if NOS inhibition would reduce this. Subjects & Interventions: 11 fetal sheep were subjected to 30 minutes transient CI in utero. 2 hours later, 5 began treatment with the NOS inhibitor NG-nitro-L-arginine (50mg.hr^-1 for 4 hours, then 18mg.hr^-1 for 3 days), and 6 with phosphate buffered saline. Using near infrared spectroscopy with optodes surgically secured to the fetal skull, changes in [CytO₂] were measured continuously for 3 days. Results: 66-72 hours post-insult the mean (SEM) change in[CytO₂] was -2.2 (0.2) mmol.L^-1 in control and -2.0 (0.4) mmol.L^-1 in treated subjects. ANOVA showed no significant difference. Conclusion: NG-nitro-L-arginine did not prevent the delayed fall in[CytO₂] following CI.