[The effect of relaxin on sperm motility. In vitro experiments with bull sperm]

We investigated the effect of relaxin (1990 pmol, 199 pmol, 19.9 pmol) on bull-sperm-motility by means of Laser-Doppler (Lazymot). We evaluated 4 parameters, i.e. percentage of motile spermatozoa and percentage of spermatozoa with good progression, mean velocity of the sperm sample and characteristic velocity of the sperm subpopulation with good progression. Amounts of 199 and 19.9 pmol relaxin did not provoke a significant change with respect to sperm motility compared with "relaxin-free" medium. The highest amount of relaxin (1990 pmol) inhibited sperm-motility with respect to all 4 parameters that had been investigated. The action of relaxin on sperm-motility depends on the amount of relaxin in the medium, e.g. activation at physiologic and inhibition at very high amounts of that substance.