Use of Spin Labels to Evaluate Effects of Cold Shock and Osmolality on Sperm

Abstract

Spin labels were used to evaluate the effects of butylated hydroxytoluene (BHT), rapid cooling to 0.degree. C and osmolality on the integrity of sperm membranes. In vitro incubation of rabbit sperm with 0.5 mM BHT prior to artificial insemination did not alter the fertilizing ability of the sperm. Sperm from 6 spp. were ranked in terms of susceptibility to membrane damage caused by rapid cooling to 0.degree. C. The integrity of bull and ram sperm membranes was destroyed by the rapid cooling BHT protected membranes of these spermatozoa from cold-induced lysis. Boar sperm membranes were porous after rapid cooling and BHT did not prevent this membrane damage. Membranes of rabbit and rooster sperm were not damaged by rapid cooling to 0.degree. C. Stallion sperm could not be analyzed because their membranes were altered by addition of reagents necessary to use the technique. The responses of bull, ram and rabbit sperm membranes to hyper- and hypo-osmotic conditions were determined. Hypotonic treatment (< 200 mOsmoles) resulted in a 50% expansion of the volume of the aqueous compartment of sperm while hypertonic (700 mOsmoles) conditions compressed the volume of the aqueous compartment to 25-30% of the volume measured at 300 mOsmoles Bull sperm, but not rabbit or ram sperm, responded as perfect osmometers between 300 and 700 mOsmoles.