Brewer T G, Berry W R, Harmon J W, Walker S H, Dunn M A
Hepatology. 1984 Sep-Oct;4(5):905-11. doi: 10.1002/hep.1840040520.
Urea synthesis is an exclusive biosynthetic function of the liver. Since the exact relationship between urea synthesis in vivo and functional liver mass remains unclear, we established an animal model using oral protein loading and measurement of resultant urea synthesis in rats. We studied rats subjected to sham operation, 40% hepatectomy, 66% hepatectomy, portacaval shunt and CCl4-induced cirrhosis. Urea synthesis was calculated as the sum of urinary urea excretion and accumulation of urea in body water during the 6-hr period after oral administration of a casein protein load equivalent to 20 gm per kg body weight. Peak urea synthesis rate in the sham-operated group of rats was 142 +/- 11 mumoles per hr per gm wet liver weight (mean +/- 1 S.D.), 473 +/- 34 mumoles per hr per gm liver protein and 80 +/- 5 mumoles per hr per mg liver DNA. This rate closely matched those of the other groups for each type of liver mass measurement. Marked reduction (p less than 0.01) of urea synthesis on a DNA basis was noted only in the CCl4-cirrhotic livers, related to the significantly higher (p less than 0.01) DNA content of the cirrhotic livers. Similarly, increased (p less than 0.05) liver protein content of the sham-operated rats when compared with the other groups was reflected in slightly lower urea synthesis rates expressed on the basis of liver protein (p less than 0.05) when compared to that of all other groups.(ABSTRACT TRUNCATED AT 250 WORDS)
尿素合成是肝脏独有的生物合成功能。由于体内尿素合成与功能性肝质量的确切关系尚不清楚，我们建立了一种动物模型，通过给大鼠口服蛋白质负荷并测量由此产生的尿素合成。我们研究了接受假手术、40%肝切除术、66%肝切除术、门腔静脉分流术和四氯化碳诱导性肝硬化的大鼠。尿素合成的计算方法是，在口服相当于每公斤体重20克酪蛋白的蛋白质负荷后6小时内，尿尿素排泄量与体内水分中尿素蓄积量之和。假手术组大鼠的尿素合成峰值速率为每小时每克湿肝重142±11微摩尔（平均值±1标准差）、每小时每克肝蛋白473±34微摩尔以及每小时每毫克肝DNA 80±5微摩尔。对于每种肝质量测量类型，该速率与其他组的速率紧密匹配。仅在四氯化碳诱导性肝硬化肝脏中，以DNA为基础的尿素合成显著降低（p<0.01），这与肝硬化肝脏中显著更高（p<0.01）的DNA含量有关。同样，与其他组相比，假手术大鼠肝脏蛋白质含量增加（p<0.05），这反映在以肝蛋白为基础表示的尿素合成速率略低（p<0.05），与所有其他组相比都是如此。（摘要截短于250字）
