Nitric oxide inhibition of human sperm motility.
OBJECTIVE
To determine the effect of nitric oxide (NO) on sperm motility in vitro.


METHODS
Normal human sperm separated by centrifugation through a discontinuous Percoll gradient and subsequent swim-up were incubated for up to 24 hours with NO donors, with and without the known NO quencher hemoglobin, as well as with agents that raise intracellular cyclic 3',5'-guanosine monophosphate (cGMP). Sperm respiration was determined by a tetrazolium-formazan spectrophotometric assay.


METHODS
Andrology laboratory.


METHODS
Absolute sperm motility and respiration.


RESULTS
Sperm incubated with the NO donors 1 mM nitroprusside, 100 to 125 microM 3-morpholinosydnonimine, and 25 to 125 microM pure nitric oxide gas dissolved in buffer were inhibited in motility in a dose-dependent fashion. The inhibition could be reversed by the NO quencher hemoglobin. Agents that raise cellular cGMP (dibutyryl cGMP or 8-bromo-cGMP) did not inhibit motility. Nitric oxide inhibited sperm respiration, as measured by the tetrazolium-formazan assay.


CONCLUSIONS
Nitric oxide reduces sperm motility, possibly by a mechanism involving inhibition of cellular respiration independent of an elevation of intracellular cGMP. Nitric oxide elaborated in the female or male genital tract in vivo could adversely influence sperm function and fertility.
Weinberg
J B
JB
Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA.
Doty
E
E
Bonaventura
J
J
Haney
A F
AF
D006152:Cyclic GMP / Q000502:physiology; D006454:Hemoglobins / Q000494:pharmacology; D006801:Humans; D008297:Male; D008981:Molsidomine / Q000031:analogs & derivatives / Q000494:pharmacology; D009569:Nitric Oxide / Q000494:pharmacology*; D009599:Nitroprusside / Q000494:pharmacology; D017382:Reactive Oxygen Species; D013081:Sperm Motility / Q000187:drug effects*
D006454:Hemoglobins; D017382:Reactive Oxygen Species; D009599:Nitroprusside; D009569:Nitric Oxide; C002385:linsidomine; D008981:Molsidomine; D006152:Cyclic GMP