Seminal plasma nitrite/nitrate and intratesticular Doppler flow in fertile and infertile subjects.

The objective of the present study was prospectively to evaluate the role of nitric oxide (NO) in modulating intratesticular blood flow and sperm function. A total of 56 males, undergoing assisted reproduction, were divided into three groups according to semen analysis: (i) normozoospermic (n = 16); (ii) oligozoospermic (n = 21); and (iii) azoospermic (n = 19). All the subjects were submitted to hormone analysis [luteinizing hormone, follicle stimulating hormone (FSH), growth hormone, testosterone, androstenedione, insulin], and to ultrasonographic (testicular volume) and Doppler (transmediastinal artery) evaluations. Plasma and seminal plasma nitrite/nitrate concentrations, and plasma insulin-like growth factor-I were assayed. All 56 patients completed the study. In normozoospermic patients, significantly greater testicular volume, lower transmediastinal resistances, and higher seminal plasma nitrite/nitrate concentrations were observed in comparison with both oligo- and azoospermic subjects. Testicular volume was inversely correlated with plasma FSH (r = -0.589; P = 0.005) and pulsatility index of transmediastinal artery (r = -0.402; P = 0.049). Furthermore, the seminal plasma nitrite/nitrate concentrations were inversely correlated with pulsatility index of transmediastinal artery (r = -0.511; P = 0.015). It was concluded that NO is involved in vascular modulation of testicular vessels and ultimately in sperm output.