Monosaccharide Transport Across Membranes of Human Spermatozoa

A method for determination of the monosaccharide uptake into human spermatozoa is described. Intracellular monosaccharide concentrations were calculated on the basis of determination of intracellular radioactivity after incubation of the cells with labelled monosaccharide and using a mathematical procedure to approximate the intracellular space of spermatozoa. The D-fructose uptake depends on the extracellular D-fructose concentration in a hyperbolic manner. Half maximal saturation is present at 4,1 mM. This corresponds closely with the lowest limit of D-fructose concentration in human fertile semen.