Metabolism of round spermatids in the rat: effect of gossypol on the glucose transport.

Low dose of gossypol (5 microM) completely inhibited uptake of 2-deoxy-D-glucose by rat spermatids. With gossypol 2-deoxy-D-glucose transport into spermatids increased curvelinearly for 10 minutes after the start of incubation, but reached a plateau afterwards, whereas without gossypol it continuously increased. The levels of fructose-1,6-bis-phosphate (FBP) and ATP were inversely correlated when the cells were exposed to glucose. However, in the presence of gossypol the levels of ATP and FBP decreased simultaneously. In addition, gossypol at 10 microM stimulated oxygen consumption when lactate was present. These results suggest that gossypol probably inhibits glucose transport into spermatids by lowering the ATP level by uncoupling respiratory chain-linked phosphorylation.