Arginine and citrulline content of isolated, microdissected airways from mice exposed to ovalbumin, as determined by HPLC after pre-column derivatization with o-phthaldialdehyde. *, significantly less than air control (Arginine, P=0.0004; Citrulline, P<0.0001). Values shown on the graph are group mean concentrations (nmol/mg total protein) ± SE, with experimental group size, N, represented as a bracketed number above the bar.