Effect of gossypol on boar spermatozoal adenosine triphosphate metabolism

The effect of gossypol on boar spermatozoal adenosine triphosphate (ATP) metabolism was investigated. Gossypol has little effect on the activities of the total spermatozoal ATPase, the spermatozoal flagellar ATPase, and the mitochondrial fragment ATPase. The membrane ATPase, being exceedingly low, has not been considered for its susceptibility toward gossypol. Gossypol uncouples spermatozoal oxidative phosphorylation. A biphasic response (stimulation at low concentration and inhibition at high concentration) has been noticed in anaerobic lactate production and hypotonically treated spermatozoal mitochondrial ATPase activity. The ATP content, either under aerobic or anaerobic condition was reduced by gossypol with the reduction threshold of ATP more sensitive in the latter. The reduction of ATP follows two different reaction kinetics in which it is stabilized at moderate gossypol concentrations but progresses along with time at high concentrations. Since the drop in motility is more sensitive than the drop in ATP content and since the flagellar ATPase is not significantly inhibited by gossypol, a motility controlling component that is more sensitive to gossypol antimotility inhibition is proposed.