Modification of human sperm metabolism by the induced release of intracellular zinc

Incubation of washed human spermatozoa in the presence of 6 mM histidine induces a release of about 75% of the zinc bound to the cells. Zinc release induced by the presence of histidine was accompanied by: 1) a significant increase in the utilization of exogenous ¹⁴C-labelled glucose, which is reflected in an increase in the production of ¹⁴CO², 2) a small but significant decrease (−14%) in the utilization of fructose when this sugar is added as exogenous substrate, and 3) a highly significant decrease in the endogenous sperm phospholipids (>30%), an effect which is not inhibited by the addition of exogenous substrates. This behavior of human spermatozoa resembles that previously described for invertebrate spermatozoa and seems to be related to the regulation of energy metabolism and probably to sperm capacitation.