Factors Influencing Uptake of Triiodothyronine-I 131 by Bull Spermatozoa. ∗

Summary

The uptake of triiodothyronine-I-¹³¹ by washed bull spermatozoa was found to have a positive association with sperm cell concentration and period of incubation with the labeled T₃. Spermatozoa suspended in a simple salt solution (2.9% sodium citrate) had a higher uptake of T₃ ¹³¹ than spermatozoa diluted in a more complex ionic medium (N-J solution). The T₃-I¹³¹ uptake by the sperm cells suspended in the 2 diluents increased at different rates with an increase in cell concentration. Within the range studied, addition of glucose to the 2 diluents had no effect on uptake of T₃-I¹³¹ by spermatozoa. Sperm cell viability greatly influenced their uptake of T₃-I¹³¹. Cells killed by continuous incubation at 38 °C or by treatment with acetic acid or sodium hydroxide had similar isotope uptake values which were significantly less than that of live cells. Spermatozoa killed by cold shock treatment, however, had the lowest uptake of T₃-I¹³¹. Whereas, formaldehyde treatment of spermatozoa resulted in uptake values significantly greater than that of live cells. A positive association between uptake of T₃-I¹³¹ and motility occurred with spermatozoa stored up to 18 days in different diluents and temperatures.