A testis-specific isoform of angiotensin-converting enzyme (ACE) has been identified in a number of mammalian species. The purpose of this study was to characterize the activity of ACE in equine spermatozoa, seminal plasma, and testis. Activity of ACE was determined in seminal plasma, ejaculated and epididymal spermatozoa from mature stallions as well as from pre- and postpubertal testis. The effect of addition of angiotensin II on equine sperm motility was also evaluated. The activity of ACE in detergent extracted sperm plasma membrane was approximately 13-fold higher than that detected in seminal plasma (93.7 mU/mg versus 7.0 mU/mg protein, respectively). Activity of ACE in equine testis was significantly higher in postpubertal than in prepubertal males (3.0 mU/mg versus 0.4 mU/mg protein, respectively), and ACE activity was reduced (P < 0.001) in a dose-dependent fashion by the addition of captopril. The effect of angiotensin II on sperm motility was evaluated by computer-assisted semen analysis in sperm incubated with angiotensin II (0, 1, 10, 100 nM) at 38.5 °C. There was no significant effect of angiotensin II on the percent motile sperm; however, there was a significant main effect of angiotensin II (P < 0.01) on the kinematic parameters beat cross frequency (BCF), average path velocity (VAP), and curvilinear velocity (VCL), respectively. In addition, there were significant stallion x concentration interactions for amplitude lateral movement (ALH), BCF, linearity (LIN), straightness (STR), and VCL. This study demonstrates that ACE activity is present in sperm membrane from ejaculated and epididymal spermatozoa and in postpubertal testis. Further studies are required to determine the role of this testis-specific enzyme.
|Number of pages||14|
|State||Published - Feb 2003|
Bibliographical noteFunding Information:
This research was supported by the John P. Hughes Endowment and by the Center for Equine Health with funds provided by the Oak Tree Racing Association, the State of California pari-mutuel fund, and contributions by private donors.
- Angiotensin-converting enzyme
- Renin-angiotensin system
ASJC Scopus subject areas
- Small Animals
- Food Animals
- Animal Science and Zoology