RESUMO
The resistance to changes in the osmolarity of boar sperm was used to measure the resistance of boar sperm cells against freezing/thawing. Semen was incubated for 5 min in different solutions ranging from about 600 mOsm to about mOsm, and at 4 degrees C, 16 degrees C or 37 degrees C (undisturbed media). This undisturbed media was constituted by NaCl, glycerol or glucose. This semen was then placed in an isoosmotic solution (disrupted solutions). Incubation in undisturbed media did not alter the percentages of viability or altered acrosomes, except when the initial incubation has been at 37 degrees C and with osmolarities above 1000 mOsm. Viability and altered acrosome statistics were strongly modified in disrupted media. These effects are dependent upon the initial osmolarity of the media, but not upon the temperature. Pre-incubation with ouabain or amiloride did not affect spermatozoa incubated at 16 degrees C in a 2211 mOsm, NaCl medium. However, in sperm incubated in this 2211 mOsm medium and then rapidly placed in an isoosmotic solution, ouabain induced a decrease in viability and an increase in altered acrosomes. Amiloride did not affect the response of cells to the disrupted medium. Some significant correlations were observed among the percentages of altered acrosomes after hyperosmotic stress and some quality parameters of the fresh boar semen, especially the motion parameters. Although the resistance to hyperosmotic stress could be a valuable parameter in assessing fresh quality analysis, its usefulness in frozen-thawed semen is compromised, since other factors beside osmotic changes are involved in the resistance of boar semen to freezing-thawing. The NA+/K+, ouabain-dependent ATP-ase activity seems to be related to the mechanisms of resistance to hyperosmotic stress in boar sperm.
Assuntos
Criopreservação/veterinária , Crioprotetores/química , Preservação do Sêmen/veterinária , Espermatozoides/fisiologia , Suínos/fisiologia , Acrossomo/química , Acrossomo/efeitos dos fármacos , Acrossomo/fisiologia , Amilorida/farmacologia , Animais , Criopreservação/métodos , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/farmacologia , Congelamento , Glucose/química , Glicerol/química , Masculino , Concentração Osmolar , Ouabaína/farmacologia , Preservação do Sêmen/métodos , Cloreto de Sódio/química , Trocadores de Sódio-Hidrogênio/antagonistas & inibidores , ATPase Trocadora de Sódio-Potássio/antagonistas & inibidores , Espermatozoides/química , Espermatozoides/efeitos dos fármacos , TemperaturaRESUMO
To study the resistance of horse spermatozoa against hyperosmotic stress, cells were incubated in solutions of 600 to 4000 mOsm(undisturbed media). Then, semen was immediately placed into an iso-osmotic solution (disrupted media). Incubation in undisturbed media decreased sperm viability in an osmolarity- and temperature-dependent manner. Viability was further decreased in disrupted media, with the effect dependent upon the initial osmolarity of the media and on the temperature. Treatment with ouabain or amiloride impaired the resistance of horse spermatozoa to hyperosmotic stress. Very few correlations were strong between viability after hyperosomotic stress and quality parameters of fresh and 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 resistance to freezing-thawing. Both Na (+)K (+) ATP-ase and the Na (+)H (+) antiporter act in the resistance to hyperosmotic stress in horse spermatozoa.