Detection of NG, NG-Dimethylarginine Dimethylaminohydrolase in the Nitric Oxide-Generating Systems of Rats Using Monoclonal Antibody

In order to elucidate the biological role of NG,NG-dimethylarginine dimethylaminohydrolase (EC 3.5.3.18), we prepared monoclonal antibodies (mAbs) against the enzyme from rat kidney and examined the distribution of the enzyme in rats. Four mAbs have been obtained by the fusion of the spleen cells from BALB/c mouse immunized with the sodium dodecyl sulfate-denatured or native enzyme and P3X63Ag8UL myeloma cells. All the mAbs were shown to bind to the denatured enzyme, but none of them could recognize the native enzyme. The occurrence of the enzyme protein in various rat tissues and cell systems such as peritoneal neutrophils and macrophages was examined using an immunoblotting technique with one of the mAbs. The immunoblotting analyses showed that the enzyme protein is widely distributed in rats, particularly, in kidney, pancreas, liver, brain, and aorta at high concentrations. Furthermore, the enzyme protein was clearly shown to exist in peritoneal neutrophils and macrophages. Since NG-monomethylarginine and NG-dimethylarginine have been suggested to be specific blockers of the systems generating nitric oxide (NO), the above findings are of great interest in connection with the regulation of the NO production in such tissues and cell systems as aorta, brain, peritoneal neutrophils, and macrophages.