Angiotensin-converting enzyme content of human spermatozoa and its release during capacitation

In this study, we demonstrated, by using known detergents, the presence of angiotensin-converting enzyme (ACE) within human spermatozoa. We determined that maximal angiotensin-converting activity is expressed by sperm incubated in capacitating conditions, whereas this activity is negligible in saline-incubated spermatozoa. We further demonstrated that not acrosomes but cytoplasmic residues contain ACE. Because follicular fluid provides the necessary conditions for a maximal angiotensin-converting activity and for capacitations' metabolic activation, we hypothesize that ACE may play its physiologic role within the female reproductive tract.