Concentrations of the amino acids L-ornithine and L-arginine in mouse lung homogenates of untreated (naïve) control as well as <i>Pseudomonas</i> infected mice treated with PBS or the arginase inhibitor 2(S)-amino-6-boronohexanoic acid (ABH).

<p>L-ornithine, the product of arginase activity, as well as L-arginine was significantly lower in naïve, compared to infected lungs (*: p<0.0001, ANOVA, respectively). ABH treatment resulted in a significant decrease in L-ornithine but increase in L-arginine concentration (p<0.001, t-test, respectively). The L-arginine/L-ornithine ratio, which can be used as an index of L-arginine availability for intracellular NOS, was reduced in infected lungs (*: p<0.0001, ANOVA) but improved in the ABH treatment group (p<0.001, t-test).