Further Observations on the Initiation of Sperm Motility1

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Abstract
Cauda epididymal rat spermatozoa were obtained by micropuncture and subjected to motility initiation studies. A previous study has shown that initiation of sperm motility requires addition of ionic solutions though no specific ion is required. The present study demonstrates the dilution of epididymal plasma is important along with the requirement for ions demonstrated previously. Initiation of sperm motility was significantly inhibited by glycerylphosphocholine (GPC) and GPC + carnitine (P<0.05). Carnitine alone significantly reduced overall sperm motility (P<0.05), but not the initiation of motility. Addition of 5 mg/ml BSA to the test diluents did not protect the spermatozoa from the effects of GPC and carnitine. It is proposed that the dilution of these compounds that occurs at ejaculation plus the concomitant addition of electrolytes allows the initiation of rat sperm motility.