Factors Influencing the Response of Ram Spermatozoa to Bicarbonate and Carbon Dioxide

The metabolism of washed ram spermatozoa was studied in the presence of bicarbonate or carbon dioxide or both under various conditions of incubation. The presence of respired carbon dioxide had little or no effect on the utilization of glucose or fructose by ram spermatozoa whether potassium was present or not. On the other hand, the addition of 6 mM sodium bicarbonate to a potassium-containing diluent stimulated oxygen uptake, glycolysis, and fructolysis by the spermatozoa. The effect of bicarbonate on substrate utilization did not depend on the maintenance of a constant concentration of carbon dioxide in the gas phase and was not influenced by prior exposure to bicarbonate. Substrate utilization was not stimulated by bicarbonate in the absence of potassium; there was a depression of oxygen uptake under these conditions.