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Erica Thornton

Effect of Ammonium Chloride on the Induction of Hyperactivated Motility in Equine Sperm

Erica Thornton, Kristin Rolke, Charles C. Love1, and Katrin Hinrichs.

Departments of Veterinary Physiology and Pharmacology and 1Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University.

Erica Thornton

Objective – The purpose of this study was to determine if motility parameters reflective of hyperactivated motility are responsive to internal changes in pH of horse sperm and to determine the effect of using a CO2 vs. air environment on motility parameters.

Animals or Sample Population – Equine semen samples from a stallion owned by Texas A&M University were used in this study.

Procedure – Sperm was suspended in a Tyrodes-lactate-pyruvate medium containing 0.02% PVA and 5 mM glucose, and then exposed to varying amounts of ammonium chloride. Motility parameters were measured by computer-assisted sperm analysis. This experiment was then repeated with media that had been in different CO2 environments.

Results – Equine sperm showed maximum indicators of hyperactivated motility at 60 min after exposure to 25 mM ammonium chloride. There was a significant interaction between ammonium chloride and the different CO2 environments.

Conclusions and Clinical Relevance – These findings suggest that motility parameters reflective of hyperactivated motility are responsive to changes in internal pH of horse sperm, with the highest response seen with 25 mM ammonium chloride at 60 min. The response of equine sperm to ammonium chloride suggests the mechanism for induction of hyperactivated motility in stallion semen is similar to that described in other species, i.e., opening of calcium channels in response to intracellular alkalinization.