Short-term preservation of fowl sperm in buffered potassium chloride

Previous research demonstrated that sperm motility is dependent upon mitochondrial calcium cycling. Thus, sperm are inactivated when extracellular calcium ions are chelated. Mitochondrial calcium cycling, however, is driven by extracellular sodium ions. The hypothesis that sperm inactivation is subject to 2 variables was tested in the present work. Sperm motility was evaluated with computer-assisted sperm motion analysis in the first experiment. Sperm became immotile within minutes when suspended in buffered isotonic potassium chloride containing calcium ions. This outcome set the stage for the second experiment in which sperm were inactivated by centrifugation through 12% (wt/vol) Accudenz prepared with potassium chloride and tetrasodium 1,2-bis-(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). Sperm mobility was the end point in the second and subsequent experiments. Potassium chloride was a suitable medium in regard to sperm inactivation with BAPTA followed by storage for 2 h at 10°C. Consequently, sperm so inactivated were reactivated after 1, 2, 3, 4, and 5 h of storage in the third experiment. Whereas pre- and postwash sperm mobility were equivalent, sperm mobility declined with time (P < 0.001) without exogenous energy in the storage medium. Therefore, the effect of 5 mM glucose was tested in the fourth experiment. In this case, recovery of sperm mobility was independent of time when sperm were stored at 10°C for 5 h (P > 0.05). Potassium chloride was replaced with potassium glutamate in the last experiment. Whereas reactivation was once again independent of time when sperm were stored with glucose (P > 0.05), greater variability was observed among observations in comparison with the potassium chloride-based medium. In summary, sperm motility was inactivated when calcium was chelated and extracellular sodium was replaced with potassium. Sperm reactivation was most consistent when chloride was the predominant extracellular anion. Collectively, these experiments demonstrate that short-term sperm storage can be achieved with simple media that promote sperm glycolysis and minimize energy demands imposed by the active transport of calcium and sodium ions.