Arginase I content of isolated airways from Balb/c mice exposed for 0 or 2 weeks to ovalbumin aerosol, +/− nor-NOHA. *, significantly greater than air control (P<0.001); **, significantly greater than air + nor-NOHA control (P<0.001). Values shown on the graph are group mean intensity ± SE, with experimental group size, N, represented as a bracketed number above the bar.