The utilization of exogenous taurine for the conjugation of xenobiotic acids in the ferret

Abstract

Although the occurrence of the taurine conjugation mechanism for various xenobiotic acids is well established, nothing is known of the source of the taurine used for this conjugation. [14C]Taurine was administered alone and in combination with 2-naphthylacetic acid or clofibric acid (both of which are known to form taurine conjugates) to to ferrets, and the 0--24 h urine collected. Of the dose of [14C]taurine, 26% was recovered in the urine in 24 h and the only 14C-containing material present was unchanged taurine. When either 2-naphthylacetic acid or clofibric acid was co-administered with [14C]taurine, 21 and 17%, respectively, of the 14C dose was recovered in the 0--24 h urine. In both cases, two 14C compounds were present--unchanged taurine (minor) and the taurine conjugate of the acid in question (major). Comparison of these results with those previously obtained with 14C-labelled 2-naphthylacetic and clofibric acids, shows that the taurine used for their conjugation is derived from a pool freely accessible to exogenous taurine. The results are discussed in terms of the availability for metabolic utilization of taurine in the animal body, and of the use of co-administration of [14C]taurine with a xenobiotic acid for the identification of taurine conjugates.

Physiological actions of taurine

“…Numerous cases of the ability of taurine to conjugate with a wide variety of chemical structures are now known. Examples include the prostaglandin E, analogue trimoprostil (377), 2naphthylacetic acid (155,256), alltrans.retinoic acid (716), and the anti-inflammatory agent, pirprofen, a 2-phenylpropionate derivative (152). Other propionate derivatives also conjugate with taurine (84).…”

Characteristics of taurine transport in rat liver lysosomes

“…Whereas the metabolism of taurine is limited, this compound has been implicated in a number of diverse processes. Besides its well-known function in bile salt synthesis (Hofmann and Small, 1967), taurine is involved in a variety of biochemical and physiological processes including osmoregulation (Thurston et al, 1980), cellular proliferation (Gaul1 et al, 1983), modulation of calcium and sodium fluxes (Sebring and Huxtable, 1985;Huxtable and Sebring, 19861, stimulation of glycolysis and glycogenesis (Kulakowski and Maturo, 1984), modulation of neuronal excitability (Oja and Kontro, 1983;Bernardi, 19851, detoxification (Emudianughe et al, 1983), membrane stabilization (Pasantes-Morales et al, 19851, antimutagenesis (Laidlaw et al, 19891, and retinal function in cats, premature or infant primates (Hayes et al, 1975;Sturman and Hayes, 19801, and possibly humans (Geggel et al, 1985;Sturman, 1986).…”

Taurine Nutrition

“…A third factor is the significant demand for cysteine used in the synthesis of fur in this species. Yet a fourth possibility that requires further documentation is whether taurine, or possibly the cysteine-containing peptide, GSH, act as primary conjugators in cats to detoxify xenobiotics and other metabolites in preparation for biliary and urinary excretion as demonstrated in the ferret (Emudianughe et al 1983). Reliance on the GSHdetoxification pathway by cats compensates for the limited availability of specific glucuronyl transferases serving this function in other species (Cullison, 1984).…”