Oxidative Metabolism of Glutamate by Testicular, Epididymal, and Ejaculated Bovine Spermatozoa in the Presence of Rete Testis Fluid and Seminal Plasma

Spermatozoa were collected by cannulae from the rete testis and cauda epididymis of conscious dairy bulls and ejaculated spermatozoa were collected by artificial vagina. Spermatozoa were washed free of fluid and incubated with glutamate-U-14C at 37 C for 60 minutes. Although glutamate probably is not a major source of energy, metabolic responses of the three cell types were distinctly different. Oxygen uptake by both testicular and ejaculated spermatozoa suspended in fete tests fluid (pI-I 7.2) was greater (P< .05) than endogenous amounts for cells suspended in Krebs-Henseleit-Ringer buffer at pH 7.2. However, rete testis fluid had little effect on the oxygen uptake of spermatozoa from the cauda epididymidis. Seminal plasma reduced the respiration rate of ejaculated spermatozoa but did not affect that of the other cell types. Identified products of glutamate catabolism by testictflar and cauda epididymal spermatozoa were aspartate, lactate, a-ketoglutarate, succinate, and ftmaarate. Oxidation of glutamate-U-14C to ~4CO~ by all three cell types was depressed (P<.05) in the presence of rete testis fluid as compared to rates for cells suspended in buffer. However, when cells were suspended in seminal plasma, 14CO2 formation was reduced (P<.05) only for testicular spermatozoa. Heat treatment of rete