The Interrelation of Oxidative and Glycolytic Processes as Sources of Energy for Bull Spermatozoa1

Although work on the respiration of spermatozoa has been reported, investigators are not in agreement as to the significance of the oxidative processes, and the nature of the substances oxidized has not been established. Redenz (1) found that various carbohydrates promoted motility only if the sperm could produce lactic acid from them. He also showed that lactic acid had no influence on motility, but it greatly increased the respiration of spermatozoa in dialyzed serum (1). The lactic acid which accumulates in semen during storage does not account for all of the glucose that disappears (2, 3). Evidence that oxidative processes promote motility was obtained by Redenx (I) who showed that in a sugar-free medium, spermatozoa soon became immotile when kept under nitrogen but retained motility in the presence of oxygen. In recent studies on the dehydrogenase activity of spermatozoa (as measured by the Thunberg technique) we observed that the methylene blue reduction time was greatly prolonged in the presence of glucose (4). This appeared to be an inhibition or sparing of oxidative processes by glucose. In the present work it was our purpose to determine the nature of the intracellular substances other than glucose which are normally utilized for energy by bull spermatozoa and to study the relationship between the oxidative and glycolytic processes. METHODS. The methods used for semen collection, motility observations and lactic acid determination, and the buffer solution in which the spermatozoa were suspended for motility and respiration studies have been previously described (4). Phosphorus was determined by the method of Fiske and Subbarow (5) using the Evelyn photoelectric calorimeter (6) to obtain the intensity of the color developed. Phospholipids were sepa-