Laser doppler flow and brain tissue PO₂ after cortical impact injury complicated by secondary ischemia in rats treated with arginine

Background: Traumatic brain injury (TBI) makes the brain susceptible to secondary insults such as ischemia. This study tested the hypothesis that L-arginine would increase regional CBF (rCBF) and brain tissue po₂ (PbtO₂) at the injury site. Methods: A secondary insult model was employed in rodents. rCBF was measured with laser doppler flowmetry (LDF) and PbtO₂ with a po₂ catheter at the impact site. Animals were randomized to receive L-arginine, D-arginine or saline intravenously, 5 minutes after impact. Results: In animals who received L-arginine, the percentage rCBF from baseline (%CBF) was higher at the impact site after impact (p < 0.001), during bilateral carotid occulation (BCO) (p = 0.001) and during reperfusion (p = 0.032). In contrast, PbtO₂ was not significantly increased throughout the experiment for the L-arginine group. Conclusions: Administration of L-arginine increased rCBF in the injured brain tissue, and resulted in better preservation of CBF during BCO than D-arginine and saline.