NITRIC-OXIDE (CENTER-DOT-NO)-INDUCED MITOCHONDRIAL INJURY AMONG CHICKEN CENTER-DOT-NO-GENERATING AND TARGET LEUKOCYTES

In an analysis of nitric oxide (.NO) production and toxicity, chicken macrophage-generated .NO inhibited mitochondrial activity in both .NO- producing macrophages themselves and lymphoid tumor targets. However, differences in targeting of mitochondrial toxicity were observed among these cells. Two chicken macrophage cell lines, HD11 arid MQ-NCSU, pr oduced .NO (measured as nitrite) dependent upon concentrations of L-ar ginine and bacterial endotoxin (lipopolysaccharide). Mitochondrial act ivity was negatively correlated with the amount of .NO produced. Using a modified MTT assay, .NO induced suppression in two mitochondrial co mplexes. Mitochondrial activity was significantly suppressed among HD1 1 cells receiving LPS alone (complex I, 63.0 +/- 5.5% suppression; com plex II, 27.9 +/- 5.2%). In contrast, mitochondrial activities in samp les receiving LPS plus inhibitor, N-G-nitro-L-arginine methyl ester (N AME; 5 mM) or 2,4-diamino-6-hydroxypyrimidine (DAHP; 5 mM), were not s ignificantly different from control values. When HD11 macrophages were cocultured with lymphoblastoid tumor targets, RECC-CU60 (T cell) or L SCC-RP9 (B cell), adding LPS (1 mu g/ml), tumor cell mitochondrial act ivity was significantly suppressed. In the generator macrophages, comp lex I was more suppressed than complex II, whereas in lymphoid targets no such difference was observed. These results indicate that .NO inhi bits complex I and II mitochondrial activity but that differential tar geting can occur among chicken leukocyte populations.