Abstract(#br)Previous reports showed that gramicidin-D (G-D), a polypeptide with antiviral and antimicrobial properties, nonoxynol-9 (N9), a common spermicidal detergent, and EDTA, a Ca-Mg chelating agent, inhibited sperm motility and cervical mucus penetration. The purpose of this study was to determine the dose-response effects of G-D, N9, EDTA and G-D + EDTA on sperm motion parameters and acrosome status. Semen specimens from known fertile donors were subjected to computer-assisted semen analysis of motility, path velocity, progressive velocity, and hyperactivation prior to and after incubation with varying concentrations of gramicidin-D, EDTA and nonoxynol-9. Each specimen was also prepared for acrosome status using rhodamine isothiocyanate conjugated pisum sativum agglutinin... (RITC-PSA). There was a significant decrease in motility by G-D, EDTA, G-D + EDTA, and N9 at all doses as compared to the fresh specimen. N9 completely immobilized all sperm at each dose. Progressive velocity and path velocity also decreased in a dose-response manner. Sperm hyperactive motility also significantly decreased in all groups. The majority of sperm remained acrosome intact following exposure to all doses tested, whereas N9 resulted in complete breakdown/release of the acrosomal contents. This study confirms previous reports that G-D, EDTA, and N9 significantly impair sperm motility and motion parameters. The effective 100% inhibitory concentration was seen only with N9, whereas G-D, EDTA, and G-D + EDTA resulted in incomplete impairment of sperm motion parameters. At the concentrations used, N9 demonstrated potent spermostatic activity. Gramicidin-D and EDTA should be further studied for their potential contraceptive spermostatic activity.