THE NITRIC-OXIDE SYNTHASE OF MOUSE SPERMATOZOA

Nitric oxide synthase (NOS) was evidenced in mature mouse spermatozoa by means of biochemical techniques and Western blot, During 120 min of incubation, 10(7) spermatozoa synthesized 7+/-2 pmol of L-[C-14]citru lline. Besides, L-citrulline formation depended on the incubation time and on the concentration of L-arginine present in the incubation medi um, Different concentrations of N-G-nitro-L-arginine methyl ester (L-N AME) but not aminoguanidine, inhibited L[C-14]citrulline formation, We stern-blot analysis of solubilized sperm proteins revealed a unique ba nd of M-r=140 kDa with the neural, endothelial and inducible NOS antis era tested, These results provide evidence that mature mouse sperm con tains a NOS isoform and that spermatozoa have the potential ability to synthesize NO, suggesting a role for endogenous NO on mammalian sperm function. (C) 1997 Federation of European Biochemical Societies.