[Effect of monosaccharides on net ion fluxes across the sperm membrane. Contribution to capacitation]

Monosaccharide supply, monosaccharide fluxes and ion fluxes play an important role in the process of capacitation of spermatozoa. Therefore we investigated the influence of D-glucose and D-fructose on the net -fluxes of Na+ and Rb+. The Na+ fluxes were very low and showed no alterations, when glucose or fructose were present in the incubation medium. On the other hand the net-Rb+-fluxes, which can be regarded as representative for the net-K+-fluxes, were energy dependent and ouabain-sensitive. Moreover D-glucose and D-fructose increased significantly the affinity of Rb+ towards its transport system. The specifity of these interactions is discussed.