Influence of bradykinin antagonists on the motility of human spermatozoa enhanced by bradykinin.

Washed human spermatozoa were coincubated at a constant concentration of bradykinin (BK) (10(-8) M) with different concentrations of the bradykinin antagonists Hoe 140, (Thi5,8, D-Phe7)-BK, and D-Arg(Hyp3, D-Phe7)-BK. In the range between 10(-10) and 10(-5) M none of the tested bradykinin antagonists was able to decrease significantly sperm motility enhanced by addition of 10(-8) M BK. Although bradykinin as the terminal effector of the kallikrein-kinin system stimulates sperm motility specifically and at low concentrations, the specific kinin antagonists failed to inhibit the effect of BK. It would appear that the action of bradykinin on motility of human spermatozoa is mediated by a highly specific mechanism. However, in contrast to earlier hypotheses, it is probably not mediated by a specific bradykinin receptor.