L-arginine attenuates endothelial dysfunction and prolongs survival in rats subjected to traumatic shock

We investigated the effects of L-arginine administration in a rat model of traumatic shock. Pentobarbital-anesthetized rats subjected to drum trauma developed a severe shock condition characterized by marked hypotension to 55-70 mmHg, a survival time of only 90 +/- 21 min, and significant increases in ileal myeloperoxidase (MPO) activity (P < 0.01). In addition, superior mesenteric artery (SMA) rings isolated from rats subjected to traumatic shock relaxed to the endothelium-dependent vasodilator acetylcholine significantly less than rings isolated from control rats (p < 0.01). Administration of L-arginine (30 mg/kg bolus + 10 mg/kg/hr, i.v.) 10 min following trauma prolonged survival time to 213 +/- 33 min (p < 0.05) and attenuated ileal MPO activity (p < 0.01) indicative of reduced neutrophil infiltration. Furthermore, SMA endothelial function was significantly (p < 0.01) preserved in L-arginine treated traumatic shock rats. These results indicate that L-arginine plays a key role in the endothelial dysfunction associated with traumatic shock and affords significant protective effects which may be manifested by an inhibition of leukocyte-endothelial cell interactions.