Abstract
The effects of freezing and thawing process on the capacity of malate-aspartate shuttle were studied in the boar spermatozoa. Shuttle capacity was indexed by measuring the ratio of lactate to pyruvate during ethanol oxidation. In the presence of glucose and ethanol, the ratio of lactate to pyruvate of washed spermatozoa was 15.1, while the ratio of frozen-thawed spermatozoa rose to 32.9. Addition of aminooxyacetate, inhibitor of malate-aspartate shuttle, caused an increase of the ratio of lactate to pyruvate in the washed spermatozoa (37.0) and the frozen-thawed spermatozoa (36.1). These results suggested that the capacity of malate-aspartate shuttle, transferring the reducing equivalents of cytosolic NADH produced during ethanol oxidation to mitochondoria, is higher in the washed spermatozoa, and is lower in the frozen-thawed spermatozoa.
