68 



W. SALISBURY 



150 280 400 



OSMOTIC PRESSURE - MILLIOSMOLES 



Fig. 4. Effect of osmotic pressure (milliosmole concentration) produced 

 by Na or K phosphate on aerobic metabolism of spermatozoa in semen. 

 Number of semen samples, n, equals 10 (Lodge and Salisbury, 1960). 



pH 7.0 which, while required in micro amounts for phosphorylation, 

 is inhibitory of respiration by mammalian spermatozoa when pro- 

 vided in the macro amounts contained in these media (Bishop and 

 Salisbury, 1955; Salisbury and Nakabayashi, 1957; White, 1956). 

 These curves for the 3-hour experiment at 37 °C illustrate the fact 

 that the effect of osmotic pressure on the metabolism of mammalian 

 spermatozoa cannot be determined regardless of the specific ions ex- 

 erting that pressure nor simply by use of one criterion of metabolic 

 activity. Presented in this fashion the curves show that maximum 

 respiration occurred in solutions hypotonic with seminal plasma. 

 The inhibitory effect on respiration is not due strictly to increasing 

 osmotic pressure but rather to the increase in concentration of the 

 phosphate and potassium ions. The experiment shows K+ to have a 

 simple additive inhibitory effect similar to that shown for K+ in 

 Fig. 3. 



Figure 5 from an earlier report (Salisbury and Nakabayashi, 1957) 

 shows the interactions observed when the cation is Na+ — a com- 

 parison of respiratory activity made during 2 hours at 37 °C for 

 semen suspended in similarly varying osmotic pressures exerted by 

 NaCl solutions and those composed of sodium dihydrogen and mono- 

 hydrogen phosphates at pH 7.0. Here the interaction of the nature 



