Free Amino Acids in the Caput and the Cauda Epididymis of Adult Rats

Abstract

To examine the content and the composition of free amino acids in the intraluminal fluid of rat epididymis, the fluids were obtained by light pressure on the dissected tissues. The amount of the total free amino acids in the pressed fluid from the caput epididymis was significantly higher than those of the cauda epididymis and the testis. Glu and Gln were predominant amino acids in the caput, and their amounts occupied more than half of the total ninhydrin reactive compounds. Such a high concentration of Glu and Gln was not observed either in the cauda or in the testis. Castration decreased Glu and increased Gln in amount. Testosterone treatment to castrated animals did not restore Glu and Gln contents in the pressed fluid from the caput epididymis to the level observed in intact rats completely. Therefore, it was assumed that a large amount of Glu in the caput was due to many factors; secretion and metabolism of epithelial cells of the gland which might be regulated by androgen, inflow of rete testis fluid, and sperm metabolism of amino acids in the epididymis. The results obtained from the caput epididymis to which the efferent duct of the testis was ligated also supported this interpretation.

Glutathione, L‐glutamic acid and γ‐glutamyl transpeptidase in the bull reproductive tissues

“…We suggest that this Glu may originate from GSH by the hydrolytic activity of y-GT. Such a reasoning is also supported by findings in the rat, which has high levels of y-GT (Kohdaira et al, 1986) and free Glu (Shimazaki et al, 1976) in the epididymal caput. However, the possibility cannot be excluded that other peptidolytic enzymes in the bull epididymis may be responsible for the production of Glu as well.…”

Gene Expression Is Differentially Regulated in the Epididymis after Orchidectomy

“…Highest expression was found in the distal caput and corpus epididymidis [62], the same regions previously shown to be involved in the uptake of L-carnitine from the bloodstream [201,203,345] Sodium-Dependent Neutral Amino Acid Transporter. Luminal fluid of the caput epididymis contains a variety of amine acids [346]. These amine acids orginate from several sources including the testis [3,347], and from direct transport from blood into epididymallumen [307].…”

“…These amine acids orginate from several sources including the testis [3,347], and from direct transport from blood into epididymallumen [307]. The amine acid concentration in lu minai fluid declines from the caput to the cauda epididymidis [346]. This decline does not result from metabolism of amine acids by spermatozoa or degradation in luminal fluid, but rather from absorption of luminal amine acids by the epididymal epithelium [348].…”

Investigation by luminal perfusion of the transfer of compounds into the epididymis of the anaesthetized rat

“…Earlier results have varied according to species and methods of collection. Such methods have involved post-mortem collection (Crabo, 1965; for review see White, 1973), or massaging, teasing or shaking the tissue to express 'luminal fluid' (Prasad et al, 1974;Huang & Johnson, 1975; Shimazaki, Yamanaka, Taguchi & Shida, 1976), but these clearly risk contamination with blood, lymph or cytoplasmic constituents leaking from cells.…”