Temporary inhibition of the initiation of motility of demembranated hamster sperm by high concentrations of ATP

Abstract

ATP is obligatory for sperm movement. When sperm from the hamster cauda epididymis were washed and exposed to a demembranation and re‐activation medium containing 0.5 or 1 mM ATP, the maximal % motility was attained almost immediately. Increasing the ATP concentration to 3 mM caused a 5 min delay in development of maximal re‐activation and a change in the beating pattern as indicated by a decrease in the % of forward progressing sperm, decreased linear velocities but unchanged curvilinear velocities. The inhibition of motility initiation by 3 mM ATP was abolished either by the inclusion of trypsin (50 ng/ml) or by a brief pre‐incubation of the sperm in the demembranation and reactivation medium before the addition of ATP. However, the beneficial effect of pre‐incubation was prevented if trypsin inhibitor was present. This indicates that the inhibition by ATP acts via a trypsin‐sensitive regulatory system, and suggests that an endogenous protease activity is necessary to overcome this. Re‐activation of sperm from the caput epididymis by all three concentrations of ATP showed similar lag periods which could also be diminished by pre‐incubation or trypsin. The results suggest that, in addition to developing their motile capacity during maturation in the epididymis, sperm exonemes change their sensitivity to ATP concentrations. Copyright © 1986, Wiley Blackwell. All rights reserved