Glass E N, Odle J, Baker D H
Department of Animal Sciences, University of Illinois, Urbana.
J Nutr. 1992 May;122(5):1135-42. doi: 10.1093/jn/122.5.1135.
Experiments were designed to develop a urinary excretion model for the study of taurine status in adult cats. The time course of changes in urinary taurine excretion in response to alterations in dietary taurine was examined in Experiment 1. Urinary taurine excretion decreased rapidly when cats were switched from a casein diet supplemented with 2000 mg crystalline taurine/kg diet to a diet containing no supplemental taurine reaching a plateau in 2 d, but the cats required 7 d to reach a plateau when switched from the nonsupplemented diet to the 2000 mg taurine/kg diet. In Experiment 2, the casein diets contained graded levels of crystalline taurine (0, 250, 500, 1000, 1500 or 2000 mg/kg). After a 7-d adjustment period, urinary taurine excretion was quantified over 5 d, and blood taurine concentrations were measured on d 6. Plasma taurine concentration increased linearly (r = 0.88) as taurine intake increased, but whole-blood taurine increased asymptotically. Taurine intakes of greater than 96 mumol/(kg body wt.d) resulted in urinary excretion rates that were 15 times greater than those occurring below this break point. We suggest that urinary taurine excretion by cats fed taurine at levels above the break point has potential for estimating taurine bioavailability in intact meat-source proteins.
设计实验以建立一个用于研究成年猫体内牛磺酸状态的尿排泄模型。在实验1中，研究了日粮中牛磺酸改变时尿中牛磺酸排泄量的变化时间进程。当猫从补充2000毫克结晶牛磺酸/千克日粮的酪蛋白日粮转换为不补充牛磺酸的日粮时，尿中牛磺酸排泄量迅速下降，2天内达到平台期，但当从无补充日粮转换为2000毫克牛磺酸/千克日粮时，猫需要7天才能达到平台期。在实验2中，酪蛋白日粮含有不同水平的结晶牛磺酸（0、250、500、1000、1500或2000毫克/千克）。经过7天的调整期后，在5天内对尿中牛磺酸排泄量进行定量，并在第6天测量血中牛磺酸浓度。随着牛磺酸摄入量增加，血浆牛磺酸浓度呈线性增加（r = 0.88），但全血牛磺酸呈渐近性增加。牛磺酸摄入量大于96微摩尔/（千克体重·天）时，尿排泄率比低于此断点时高15倍。我们认为，给猫喂食高于断点水平的牛磺酸时，尿中牛磺酸排泄量有可能用于估计完整肉类来源蛋白质中牛磺酸的生物利用率。
