Effect of steroid hormones on membrane sugar transport in human spermatozoa.

Using the model of exchange transport, we found that glucose transport through the human spermatozoa membrane (447 +/- 54 pmoles/min/10(8) cells) is probably the rate-limiting step in sugar utilization. Sugar transport was more efficient for glucose than for fructose (182 +/- 32 pmoles/min/10(8) cells) and depends on a highly asymmetric carrier with at least two transporting sites. Transport was drastically dependent on pH with an optimal pH of 7.4, showing a decrease of more than 60% with a change of 1 pH unit. Testosterone and 17-B estradiol increased the amount of transported sugar (619 +/- 73 and 922 +/- 110 pmoles/min/10(8) cells, respectively), while progesterone has no effect.