Oxygen uptake was increasingly stimulated during the first 20-minute interval by each increase in the amount of glycerol added ([Fig. 9]). After the first 20 minutes, the rate of oxygen utilization decreased at the two higher levels of glycerol but persisted at 4 percent. The rate of oxygen consumption for the first 20-minute period at the 4-percent glycerol level was 130 percent that of the control to which only sodium citrate had been added. At 8 and 12 percent the values for the period were 144 and 192 percent, respectively, of the control rate.
| Effect of glycerol and glycerol-plus-catalase additions on sperm motilityduring incubation at 37° C. | |
| (Fig. 10) | |
With each increase in glycerol level, motility was reduced during the incubation period. This is shown in [Figure 10] along with the effect on motility of adding catalase, which is discussed in the next section.
Effect of glycerol-plus-catalase on oxygen uptake of diluted semen. Certain bacteria have been shown to break glycerol down, forming hydrogen peroxide as follows:
Glycerol + oxygen → lactic acid + hydrogen peroxide.
Hydrogen peroxide is known to be detrimental to sperm. The addition of glycerol to diluted semen first increased oxygen uptake and then reduced it. Since a reduction in sperm survival followed, some harmful action must have taken place with the addition of glycerol at 37° C. To test whether this action could be due to the release of hydrogen peroxide as occurs in certain bacteria, glycerol with catalase—the enzyme which breaks down hydrogen peroxide—was added to a portion of 8 diluted semen samples and the oxygen uptake was recorded. Comparison of the resulting oxygen uptake with glycerol and with glycerol plus catalase is shown in [Figure 11].
