ATP concentration of human spermatozoa: lack of correlation with sperm motility

The primary source of energy for sperm motility is intracellular adenosine 5'-triphosphate. We studied the relationship between the concentration of ATP and sperm motility in normal semen donors and in a series of male infertility patients. The ATP concentration was determined by the firefly luciferin-luciferase assay, and sperm motility was quantitated by the turbidimetric method. Although the patient population demonstrated a significantly lower sperm motility than the donor population, we found no significant difference between the two groups in the intracellular concentration of ATP. Thus, the data indicate that the poor sperm motility observed in some of the patients' specimens was not associated with abnormally low levels of ATP. In separate experiments the intracellular concentration of ATP decreased gradually with time at approximately the same rate at which sperm motility declined. Both factors had decreased by 50% approximately 3 hours after collection.