OBJECTIVETo investigate the relationship of nitric oxide (NO) and nitric oxide synthase (NOS) with varicocele (VC) infertility.

METHODSFifty-three infertile men, 21 with varicocele and 32 with subvaricocele, were enrolled as Group 1, 29 infertile patients with oligoasthenozoospermia but without varicocele as Group 2 and 28 normal fertile controls as Group 3. The NO content and NOS activity in the seminal plasma and peripheral blood were measured by nitric acid reductase method, and the semen parameters of VC determined by computer-assisted semen analysis (CASA).

RESULTSSignificant differences were noted between Group 1 and the other two in the NO content and NOS activity in the seminal plasma (P < 0.05) but not in the peripheral blood (P > 0.05). In Group 1, the NO content and NOS activity were increased in both the seminal plasma and peripheral blood with the enhanced diameter of the varicose spermatic vein, with a significant difference only in the seminal plasma between the varicocele and subvaricocele patients (P < 0.05), and the same increase was observed with decreased sperm concentration (> or = 20 x 10(6)/ml and < or = 10 x 10(6)/ml) and motility (> or = 50% and < or = 25%), with significant differences (P < 0.05).

CONCLUSIONNO plays an important role in the VC-induced decrease of seminal quality. For the diagnosis of VC, the determination of the NO content and NOS activity in the seminal plasma is of more significance than that in the peripheral blood, and the earlier the determination, the greater its clinical value for both the diagnosis and treatment of VC.