RESISTANCE TO OSMOTIC-STRESS OF HORSE SPERMATOZOA - THE ROLE OF IONICPUMPS AND THEIR RELATIONSHIP TO CRYOPRESERVATION SUCCESS

To study the resistance of horse spermatozoa against hyperosmotic stre ss, cells were incubated in solutions of 600 to 4000 mOsm(undisturbed media). Then, semen was immediately placed into an iso-osmotic solutio n (disrupted medial. Incubation in undisturbed media decreased sperm v iability in an osmolarity-and temperature-dependent manner. Viability was further decreased in disrupted media, with the effect dependent up on the initial osmolarity of the media and on the temperature. Treatme nt with ouabain or amiloride impaired the resistance of horse spermato zoa to hyperosmotic stress. Very few correlations were strong between viability after hyperosomotic stress and quality parameters of fresh a nd frozen-thawed horse semen. The results indicate that the usefulness of resistance to hyperosmotic stress in assessing frozen-thawed semen quality is compromised, since other factors are involved in the resis tance to freezing-thawing. Both Na+/K+ ATP-ase and the Na+/H+ antiport er act in the resistance to hyperosmotic stress in horse spermatozoa. (C) 1997 by Elsevier Science Inc.