Taurine, radioactive

Growing chicken128 and hens129 utilize sulphate sulphur for cystine synthesis. Biological radio-tracer experiments130 with Na235S04 (10 fiCi) have shown that over 65% of the 35S administered to a 24-hour-old embryo is incorporated into taurine of the chick. No radioactive cystine, methionine or cysteic acid was detected in the hydrolysate obtained from the embryo and only a small portion of total taurine-35S occurs as taurocholic acid. The embryo is unable to utilize sulphate sulphur for cystine synthesis. 

The demonstration by Bergstrom et al. (4,5) in 1953 of the conversion of deoxycholic acid to taurocholic acid in the rat in vivo and by rat liver slices paved the way for studies on 7a-hydroxylation and conjugation of bile acids. The early work on the synthesis of bile acid conjugates in vitro utilized slices or homogenates of rat and human liver, and the enzymatic reaction was followed by the incorporation of radioactivity from carboxyl- C-labeled bile acids into the corresponding taurine and glycine conjugates (6,7). The... 

The findings of Fidge et al. (1968) were consistent with earlier observations (Zachman and Olson, 1965 Zachman et al., 1966) that retinoic acid, injected into the portal vein, was rapidly metabolized and excreted in the bile. The labeled compounds found in bile consisted of a mixture of polar metabolites, most of which were more polar than free retinoic acid. One of the metabolites of retinoic acid in bile has been identified as retinoyl -glucuronide (Dunagin et al., 1965 Zile et al., 1980, 1982a Swanson et al., 1981). Other polar metabolites account for most of the radioactivity in bile after administration of labeled retinoic acid to rats (Zile et al., 1980, 1982a) one of these has been identified as a taurine conjugate of a retinoic acid metabolite (Skare et al., 1982). 

When the sodium concentration in the mucosal fluid is reduced tenfold, in addition to radioactive L-alanine, two other radioactive substances appear in the intracellular fluid taurine and ethionine sulfoxide. But the specific activity of alanine in the intracellular fluid still has the same value as in the mucosal saline. 

Fig. 1 CYSTEAMINE OXYGENASE ACTIVITY IN HUMAN LIVER 30 mg of human liver homogenate, j> tained by biopsy, were incubated, as reported in the text, with S-cysteamine in the presence of cofactor. A = zero time, B = 4 hours incubation. The radioactive peaks correspond to taurine (l), hypotaurine (2) and unreacted cysteamine (3).

Relative distribution of radioactivity in hypotaurine (clear columns) and taurine (hatched columns) in the liver and kidney of adult mice in vivo at varying intervals after an intramuscular injection of [ S]hypotaurine. 

Experiments undertaken to determine whether or not methionine sulfur can be converted to taurine sulfur by the dog and the rat tended to show positive results. Taurine containing radiosulfur was isolated from the bile of fistula dogs given radioactive methionine. A large part of the labeled sulfur (as methionine and cystine) is contained in the proteins of fasted bile fistula dogs and rats fed methionine. 

These authors fed methionine containing radioactive sulfur to dogs and isolated from the bile of these animals taurine which contained the same sulfur. They state that the oxidation of methionine sulfur to taurine also takes place in rats. 

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