Relationship between human seminal kallikrein-kinin system and spermatogenesis

The concentration of kallikrein and the activity of angiotensin converting enzyme (ACE) in the semen specimens mainly from patients with male sterility and from those who were subjected to vasoligation, and in the prostatic fluid specimens from normal controls were determined by radioimmunoassay (RIA) and the modified Cushman's method, respectively. The kallikrein level in the semen from normal control was 40.4 +/- 21.3 ng/ml which was more than 10 times that in the blood. The value tended to increase with the decrease of the number of sperm. But there was no significant correlation between the kallikrein level and the sperm motility. The seminal kallikrein level from the patients subjected to vasoligation and that in the prostatic fluid from the normal male were 20-28 ng/ml. Therefore, that amount was considered to be secreted from the prostate gland. The results of column chromatography suggested that kallikrein combined with the other substances to form a high molecular compound in the semen. The ACE activity was 94.9 +/- 10.9 nmol/ml/min in the semen from the normal control, which was about three times that in the blood. Similar to kallikrein, it tended to decrease with the increase of the number of vasoligation and that in the prostatic fluid from the normal males was higher than that in the semen from the normal control and patients with male sterility, it was estimated that the considerable amount of ACE was secreted from the prostate gland.