114 PIERRE H. GONSE 



mildly washed cells which usually do not respond to succinate; on 

 more thoroughly washed spermatozoa, however, succinate evokes a 

 tenfold increase in respiration, while lactate loses its effect. This can 

 be interpreted as showing that extensive washing destroys both the 

 normal impermeability to succinate and lactic acid dehydrogenase 

 activity of the cell; succinic oxidase activity, however, persists. With 

 the proper spermatozoan preparation and adequate substrate one 

 always observes, on difference spectra at room temperature, the aero- 

 bic steady state which persists for a few minutes. A partial reduction 

 of cytochromes a s , a, c, b, of pyridine nucleotides, and of flavopro- 

 teins is detected after addition of lactate or succinate (Figs. 7 and 8). 

 On low-temperature "stabilized steady states" cytochrome c x also ap- 

 pears involved. 



The effect of antimycin A in the presence of lactate is also shown 

 in Fig. 7. In this particular experiment respiration was inhibited by 

 87%. The increased reduction of cytochrome b or b(d) is shown both 

 here and in Fig. 6. Antimycin A is a specific inhibitor of electron 

 transfer between cytochromes b and c ± or c (Chance and Williams, 



Fig. 7. Difference spectra of bull spermatozoa at 25°C. Cells washed 

 and suspended in RP, pH 7.3. Sample H 513. Solid line: (lactate 20 mM, 

 aerobic) — (aerobic, endogenous substrates). Dashed line: (antimycin A 

 4 x 10- 6 M, lactate, aerobic) — (lactate, aerobic). TN a was 0.8 sec -1 . 

 Reduction by lactate in per cent: 4.5 (cyt a^), 13 (a), 35 (c + c x ), 41 (b), 23 

 (FP). 



