RESUMO
<p><b>OBJECTIVES</b>To understand the relation between nitric oxide (NO) level in seminal plasma and male fertility.</p><p><b>METHODS</b>The levels of NO in seminal plasma of 174 fertile males and 217 abnormospermia patients were measured by using the reductase of nitric acid, Greiss reagent and spectrophotometry.</p><p><b>RESULTS</b>1. NO was found in all 174 samples (20-49 years) of fertile males which was (27.78 +/- 5.81) mumol/L. The NO level in seminal plasma in fertile males was became higher after age 40, and there was no significant difference between 20-29-year-old [(26.25 +/- 5.52) mumol/L] and 30-39-year-old[(28.11 +/- 5.87) mumol/L]. But the group of 40-49-year-old[(30.17 +/- 6.14) mumol/L] had a higher level of NO in seminal plasma than 20-29-year-old (P < 0.05). 2. The seminal plasma samples from nine types of abnormospermia were measured, which all had a higher level of NO than fertile males. In abnormospermia, the level of NO in seminal plasma of the patients with single abnormality increased slightly, two abnormality obviously increased, and the highest level of NO in seminal plasma appeared in three abnormality.</p><p><b>CONCLUSIONS</b>This results confirmed that proper level of NO in seminal plasma may regulate the spermatogenesis.</p>