Edgar S E, Hickman M A, Marsden M M, Morris J G, Rogers Q R
Department of Physiological Sciences, School of Veterinary Medicine, University of California, Davis 95616-8741.
J Nutr. 1994 Jan;124(1):103-9. doi: 10.1093/jn/124.1.103.
The ability of cats to use dietary cysteic acid as a precursor for taurine was examined. For 39 wk, six groups of four specific-pathogen-free cats each were fed purified diets that provided either 1.25 g taurine or 0, 1.0, 2.0, 10 or 20 g cysteic acid/kg diet. Concentrations of taurine in plasma and whole blood were measured weekly for 13 wk and monthly until 39 wk. Muscle concentrations of taurine at 12 wk were measured on a biopsy sample of the semitendinosus muscle. Fecal and urinary excretions of taurine and cysteic acid at 17 wk were measured. Concentrations of taurine in plasma and whole blood were linearly and positively correlated with cysteic acid in the diet (r2 = 0.88). Urinary taurine, a major route of excess taurine excretion, was positively correlated with the cysteic acid concentration of the diet (r2 = 0.94). Muscle and whole-blood taurine concentrations were also positively correlated (r2 = 0.96) with dietary cysteic acid concentration. Gross and histopathological examinations were performed on cats fed diets containing 20 g cysteic acid/kg diet. No adverse gross clinical signs were observed in cats fed any diets containing cysteic acid; minor histopathologic changes of the pancreas and thyroid were found in three of four cats fed 20 g cysteic acid/kg diet. Results suggest that cats are able to use dietary cysteic acid as a precursor for taurine biosynthesis.
研究了猫利用膳食中的半胱磺酸作为牛磺酸前体的能力。在39周的时间里，将六组每组四只无特定病原体的猫喂食纯化日粮，这些日粮分别提供1.25 g牛磺酸或每千克日粮含0、1.0、2.0、10或20 g半胱磺酸。在13周内每周测量血浆和全血中的牛磺酸浓度，直至39周则每月测量一次。在12周时，对半腱肌活检样本测量肌肉中的牛磺酸浓度。在17周时测量粪便和尿液中牛磺酸和半胱磺酸的排泄量。血浆和全血中的牛磺酸浓度与日粮中的半胱磺酸呈线性正相关（r2 = 0.88）。尿液中的牛磺酸是牛磺酸过量排泄的主要途径，与日粮中的半胱磺酸浓度呈正相关（r2 = 0.94）。肌肉和全血中的牛磺酸浓度也与日粮中的半胱磺酸浓度呈正相关（r2 = 0.96）。对喂食每千克日粮含20 g半胱磺酸的猫进行大体和组织病理学检查。在喂食任何含半胱磺酸日粮的猫中均未观察到明显的大体临床症状；在喂食每千克日粮含20 g半胱磺酸的四只猫中，有三只发现胰腺和甲状腺有轻微的组织病理学变化。结果表明，猫能够利用膳食中的半胱磺酸作为牛磺酸生物合成的前体。
