Elevated nitric oxide concentration in the seminal plasma of infertile males: nitric oxide inhibits sperm motility.

PROBLEM

To evaluate the effect of nitric oxide in the seminal plasma on sperm motility.

METHOD

Seminal plasma concentrations of NO2-, a stable end product of nitric oxide, of 108 males of infertile couples and 15 proven fertile donors were measured and compared with spermatogram parameters. Motile sperm was incubated with a nitric oxide-generating drug, sodium nitroprusside, for 6 hr in the absence or presence of oxyhemoglobin, an inhibitor of nitric oxide.

RESULTS

The NO2- concentration in the seminal plasma was 6.58 +/- 0.5.6 microM in 26 infertile males with leukocytospermia, 5.51 +/- 0.25 microM in 82 infertile males without leukocytospermia, and 3.91 +/- 0.16 microM in 15 controls. There was a significant correlation between the NO2- concentration and sperm motility. Sodium nitroprusside reduced the sperm motility in a dose- and time-dependent manner and its reduction was completely inhibited by the addition of oxyhemoglobin.

CONCLUSION

These findings indicate that nitric oxide concentration in the seminal plasma of infertile males is elevated and that nitric oxide is an inhibitor of sperm motion.