Western blotting of NOS isoforms in lumbar dorsal horn of normal and monoarthritic rats. Left panel, neuronal nitric oxide synthase (nNOS); middle panel, inducible nitric oxide synthase (iNOS); right panel, endothelial nitric oxide synthase (eNOS). Lane 4, lumbar dorsal horn of normal rat; lane 5, lumbar dorsal horn of monoarthritic rat. The positive and the negative controls are shown in lanes 2 and 3, respectively (for a description of the positive and negative controls see the Materials and methods section). The standards for molecular mass were run in lane 1, as shown by the adjacent marks. Arrows indicate the position of bands detected by the monoclonal antibodies at the expected sizes for nNOS (155 kDa), eNOS (140 kDa) and iNOS (130 kDa).