Effect of the Membrane Active Ionophore, Nigericin, on Motility of Ram Spermatozoa

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Abstract
Ram spermatozoa diluted in Ringer-fructose-phosphate to a concentration of 5 × 106 cells/ml, were exposed to continuous variations of pH, using HCl or NaOH. Percent of motility and ATP level were measured within 1—2 min from the pH change. High percent of motility was observed in the range of 2 pH units, between pH 6.5 to 8.5, regardless of the source of the ATP production: mitochondria, fructolysis, or both. In the presence of nigericin (H+/K+ exchanger), two peaks of high motility were observed: one at alkaline pH (7.8—8.3) and the other at acidic pH (6.5—7.0). When nigericin was added to cells inhibited by 2-deoxyglucose (possessing mainly mitochondrial motility), the high percent of motility was noted at the alkaline pH (7.2—7.6). However, when nigericin was added to cells inhibited by Antimycin-A (possessing mainly fructolytic motility), the high percent of motility was observed at the acid pH (6.0—6.7). The ATP level was correlated with the pattern of the motility.