The nitric oxide synthase of mouse spermatozoa

AbstractNitric oxide synthase (NOS) was evidenced in mature mouse spermatozoa by means of biochemical techniques and Western blot. During 120 min of incubation, 107 spermatozoa synthesized 7±2 pmol of l-[14C]citrulline. Besides, l-citrulline formation depended on the incubation time and on the concentration of l-arginine present in the incubation medium. Different concentrations of NG-nitro-l-arginine methyl ester (L-NAME) but not aminoguanidine, inhibited l-[14C]citrulline formation. Western-blot analysis of solubilized sperm proteins revealed a unique band of Mr=140 kDa with the neural, endothelial and inducible NOS antisera tested. These results provide evidence that mature mouse sperm contains a NOS isoform and that spermatozoa have the potential ability to synthesize NO, suggesting a role for endogenous NO on mammalian sperm function