Research Description:

Dietary Arginine Does Not prevent Neutrophil Accumulation in the Lungs of Aged Mice
Studies have shown that administration of exogenous L-arginine prevents lipopolysaccharide (LPS)-induced lung neutrophil accumulation. Because nitric oxide (NO) production is decreased in the aged, we examined the role of dietary L-arginine, a substrate for local NO production, in neutrophil accumulation in the lungs of young versus aged mice. One-mo. And 22-mo old CB6F1 mice were fed a defined diet (AIN 93G or AIN 93M) containing arginine (2 g/100 g, n=10-14 per age) or a controlled diet made isonitrogenous with alanine (n=12-14 per age), for two weeks. On day 14 of the diet, the LD50 of LPS was administered intraperitoneally to half the mice in each age and diet group. The other half were administered saline intraperitoneally. Four hours post challenge, lungs were removed and neutrophil content was determined by myeloperoxidase (MPO). After LPS, lung MPO activity increased 6-fold regardless of age or diet (P<0.05). There were no significant differences in neutrophil accumulation between diet or age. These data suggest that a diet supplemented with arginine does not affect in vivo neutrophil accumulation in the lungs of young or aged mice. Supported by: ILSI N.A. Future Leader Award.