SPECIFICITY OF ATP FOR THE INITIATION OF FLAGELLAR MOTILITY OF HAMSTER SPERM

Hamster sperm collected from the cauda epididymis were washed and the pellet diluted in a medium containing Triton x 100 (Sigma, Saint Louis, MO, USA) to dissolve the cell membrane and then reactivated with various concentrations of ATP (0-3 mM). Spermatozoal axonemes were initially immotile but the maximal percentage motility was obtained almost immediately following addition of 1 mM ATP. A stepwise increase in the concentration of ATP caused a 5-min delay in development of maximal reactivation and a change in the beating pattern as indicated by a decrease in the percentage of reactivating sperm. Under the same experimental condition GPT, UTP, CTP, and AMP failed to initiate the axonemal motility. In demembranated sperm reactivated by ADP, however, the beat frequency was lower compared with that reactivated by ATP. Pretreatment of the sperm with the mitochondrial phosphorylation blockers oligomycin and 2'4'-DNP (dinitrophenol) failed to inhibit the axonemal movement, although the presence of the dynein ATPase inhibitor, vanadate, was able to inhibit the reactivation. These results suggest that the exogenous ATP, but not the mitochondrial ATP, is responsible for axonemal motility.