The role of potassium ion and extracellular alkalization in reinitiation of human spermatozoa preserved in electrolyte-free solution at 4°C

Objective To elucidate reinitiation factors in human spermatozoa preserved in the electrolyte-free solution at 4°C. Setting Andrology laboratory of our hospital. Patients Semen samples were obtained from patients attending our infertility clinic. Interventions Ejaculated sperm were centrifuged and washed using the electrolyte-free Percoll gradient and then were preserved for 1 week at 4°C. Main Outcome Measures The motility of preserved sperm was incubated and analyzed after the addition of electrolyte solutions. Results The motility rate was 9.6% when the preserved sperm were incubated directly. The motility increased to 35.1% after alkalization (pH 7.8) and further increased to 40.7% when 0.1mM KC1 was added. The motility decreased to 1.4% in a weak acidic solution (pH 6.8), however, the addition of a ≥10mM concentration of NaCl or ≥0.1mM concentration of KC1 increased in motility. The motility rate in 40mM NaCl and 40mM KC1 (pH 6.8) was 19.8% and 31.5%, respectively. The restoration of motility by NaCl was inhibited by 1mM amiloride. The motility also rose to 54.1% and 32.3% in 0.04% NH3 and 80mM NH 4 C1 solution, respectively. Conclusions The reinitiation of preserved spermatozoa was induced by potassium ion and extracellular alkalization.