IONIC AND OSMOTIC CONDITIONS 



69 



5 10 15 



OSMOTIC PRESSURE IN ATMOSPHERES 



Fig. 5. Interaction of NaCl and NaHP0 4 and osmotic pressure on aer- 

 obic metabolism. Number of semen samples, n, equals 11 for curve A and 

 4 for curve B (Salisbury and Nakabayashi, 1957). 



of the anion and its concentration as it affected respiration was 

 marked. 



Thus a simple statement of the optimum osmotic requirements 

 of mammalian spermatozoa is impossible. To maximize spermatozoan 

 motility and aerobic metabolic activity an osmotic pressure equiva- 

 lent to a A F.P. of fresh seminal plasma (Rothschild and Barnes, 

 1954a) and of the follicular fluids (Olds and VanDemark, 1957b) 

 (— 0.53 °C) is best. Bishop and Salisbury (1955) several years ago 

 concluded that, for optimum respiration and livability of spermatozoa 

 in semen during 4-hour incubation at 37 °C, dilution with a 0.9% 

 NaCl solution gave better results than other solutions commonly 

 used. Though cells washed in 0.9% NaCl and resuspended in it 

 utilized fructose and motility was sustained, a minimum require- 

 ment for K was not then recognized. When excessive washing for 

 removal of substrate was required in some experiments, White (1953) 

 found that minimum levels of K+ were necessary in the washing 

 fluid to maintain subsequent metabolic activity in the presence of 

 substrate. In other experiments Brochart (1951) found that after 

 storage of bull spermatozoa for several days the addition of water or 

 a hypotonic solution to the suspension medium of yolk-citrate re- 

 stored optimum motility. This last result was most likely due to the 



