Abstract: 132

NITRIC OXIDE: EFFECTS ON SPERM MOTILITY AND PRODUCTION BY THE SPERMATOZOA IN FATHEAD MINNOW, Pimephelas promelas.

Christopher P. Montville¹ , Ernst V. Arnold² , Elizabeth Sagan² , Margaret Creech¹ , Michael C. Muzinich¹ , D. Scott Bohle² , Brian J. Hubbard¹ , Robert W. Atherton¹
Department of Zoology-Physiology University of Wyoming, Laramie WY ¹
Department of Chemistry University of Wyoming, Laramie WY ²

Computer Assisted Sperm Analysis (CASA) has been used to determine that the standard nitric oxide (NO) donor sodium nitroprusside at 1 x 10^-6 M concentration significantly enhanced sperm motility in the fathead minnow, Pimephelas promelas [Creech et al., J Androl 1998; 19:667-674]. In the present work, two previously untested NO donors spermine NONOate and pyrrolidine NONOate, also at 1 x 10^-6 M concentrations, significantly increased VCL (curvilinear velocity), VSL (straight line velocity), and VAP (average path velocity) sperm motility parameters. Importantly, L-arginine, the substrate for nitric oxide synthase (NOS), and two NOS competitive inhibitors aminoguanidine hemisulfate and L-NMMA, at 526 µM (IC₅₀) and 3.9 µM (IC₅₀) respectively, had no affect on sperm motility. This supports the hypothesis that NO production itself does not occur in sperm. In further support of this hypothesis, NO production was not detected by electron spin resonase (ESR) in sperm controls or in samples incubated with L-arginine. In addition, high performance liquid chromatography (HPLC) did not detect nitrite (NO₂^-) or nitrate (NO₃^-), the by products of NO degradation in solution, in analyzed sperm samples. Enhancement of sperm motility by previously untested donors and the absence of NO in fish seminal fluid indicate that NO produced by unfertilizaed ova may act as a sperm chemokinetic agent in teleost reproduction. Supported in part by the Department of Zoology-Physiology, University of Wyoming; Wyoming State Technology and Energy Authority and the following grants [D.S.B.] NIH GM 53828; AHA 94017580, and NSF-EPSCoR 9550477.

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