Figure 1. Serum NO_x^– levels in TNF- or LPS-treated WT, iNOS^–/–, and BMT mice. Mice were injected iv with PBS, 12.5 µg TNF, 300 µg E. coli LPS, or 150 µg S. abortus equi LPS. Serum NO_x^– levels were determined 8 h later. ***P < 0.001, as compared with corresponding treatment in the WT to WT group. Plotted are means ± SD; numbers above bars are number of mice. Insert: PCR reactions, specific for the WT or deficient iNOS allele, were performed on WBC DNA of BMT mice. I: WT to WT, II: iNOS^–/– to WT, III: WT to iNOS^–/–, IV: iNOS^–/– to iNOS^–/–, M: marker.