Determination of nitric oxide synthase activity in rat, pig and rabbit prostate glands

The conversion of L-arginine to L-citrulline by nitric oxide synthase and other enzymes was studied in rat, pig and rabbit prostate glands by incubating preparations of the glands with [3H]L-arginine and measuring [3H]L-citrulline formation. The nitric oxide synthase inhibitor N(G)-nitro-L-arginine, (100 microM) reduced [3H]L-citrulline production in preparations from all three species. The arginase inhibitor L-valine (60 mM) inhibited [3H]L-citrulline production in rat and pig but not in rabbit prostate preparations. Omission of calcium or NADPH significantly reduced nitric oxide synthase-like activity in preparations from all three species but arginase-like activity was not significantly affected. The results indicate that the rabbit prostate contains the greatest amount of calcium-dependent nitric oxide synthase activity, the rat and pig prostates also have arginase-like enzymatic activity and the rat prostate contains an additional unidentified enzyme that converts L-arginine to L-citrulline.