IONIC AND OSMOTIC CONDITIONS 75 



Table V. Effects of calcium concentration, potassium concentration, and 

 pH on aerobic metabolic activity of washed ejaculated spermatozoa ' b 



" n, the number of semen samples, equals 8. 

 6 Cragle and Salisbury (1959). 



with K+ concentration. On the other hand, glycolysis varied directly 

 with pH, inversely with K+, and showed an interaction of osmotic 

 pressure and K+ concentration. 



An Interaction with Divalent Calcium 



The effect of calcium in a citrate-bicarbonate buffer on aerobic 

 metabolism of washed bull sperm cells is shown in Table V. This 

 cation has presented an enigma. The amount of calcium in the epi- 

 didymal fluids is no higher than the level of calcium in blood, being 

 less than 10 mg/100 ml. However, three to four times as much cal- 

 cium is found in fluid in the seminal vesicles which, also, produces 

 the citric acid of semen and, presumably, this would bind the cal- 

 cium and remove it from chemical reactions. Calcium has been re- 

 ported to stimulate (Fleig, 1909; Foote, 1950) and to inhibit (Black- 

 shaw, 1953; Lardy and Phillips, 1943) motility (Blackshaw, 1953; 

 Fleig, 1909) and metabolism (Bishop and Salisbury, 1955; Foote, 

 1950) of spermatozoa. As shown in Table V when combined with 

 variations in pH and K+ in citrate-bicarbonate the calcium ion did 

 not inhibit 2 uptake or motility. If anything, the higher level of 

 calcium increased respiration and completely removed the inhibi- 

 tory effect of K+ on glycolysis (Cragle and Salisbury, 1959). These 

 results suggest an important function of calcium in initiating sperm 

 motility at the time of ejaculation. However, in future tests of this 

 point straightforward, single-variable experiments involving calcium 

 will not provide the answers as to its function in vivo. That func- 

 tion can be ascertained only if the experiments conducted reflect 

 most of the natural variables involved. 



