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G. W. SALISBURY 



tion of such cells washed and resuspended in 0.9% NaCl immediately 

 after collection (Fig. 11, lib) and after storage for 24 hours at 5°C 

 in the inhibitory collection diluent (Fig. 11, lb). Also shown is the 

 respiration of the same cells (la and Ha) in the presence of fructose. 



The data shown suggest that during the 24-hour storage a change 

 in the cell occurs, perhaps by diffusion of a metabolic regulator from 

 the cells as suggested by the Wisconsin workers (Lardy, 1953; 

 Lardy et al., 1945, 1949), which results in increased respiration both 

 in the absence and presence of exogenous substrate. The observa- 

 tion is entirely in accord with those made on bull epididymal cells 

 by Lardy et al. (1949), and on C0 2 -inhibited spermatozoa incubated 

 for 24 hours at 37 °C by Salisbury et al. (1960). 



EVIDENCE FOR A MINIMUM CO, REQUIREMENT 



From time to time data have been obtained in our experiments 

 indicating a minimum requirement for free C0 2 . One of these ob- 

 servations for aerobic conditions is shown in Table III (Salisbury 

 and Kinney, 1957). Later it was found that optimum oxygen uptake 

 by ejaculated spermatozoa in semen can occur only when CO, in 

 amounts normally respired is present (Lodge and Salisbury, 1960). 

 Lodge (1960) also has shown, Fig. 12, that washed epididymal-like 



Fig. 12. Effect of pC0 2 on anaerobic metabolism of washed epididy- 

 mal-like spermatozoa in IVT Na diluent at 37°C. Number of semen samples, 

 n, equal 4; IVT is Illini variable-temperature diluent (Lodge, 1960). 



