Influence of temperature on hexose transport by round spermatids of rats

Transport of 3-O-methyl-D-[¹⁴C]glucose in vitro by round spermatids was more rapid at 34 than at 37°C and more rapid at 37 than at 40°C. The difference between values at 34 and at 37°C was reversed by changing the spermatids from 37 to 34°C at various times during a total incubation of 1 h. The effect of 37°C relative to 34°C was exerted on K(m) for the transport process; V(max) was unaltered. Inhibition by 37°C relative to 34°C was exerted on influx; efflux was the same at both temperatures. A fraction of cells from rat testis enriched in spermatocytes but free from spermatids showed greater transport at 37 than at 34°C. These results indicate that one metabolic effect of body temperature (37°C) as opposed to scrotal temperature (34°C) is inhibition of glucose transport into round spermatids. This may contribute to the defective spermatogenesis that can occur in abdominal testes.