Palekar A G, Angadi C V
Arch Biochem Biophys. 1985 Mar;237(2):430-2. doi: 10.1016/0003-9861(85)90296-6.
Earlier studies have revealed, upon hypophysectomy, a specific increase in mitochondrial urea cycle enzymes, namely carbamyl phosphate synthetase and ornithine transcarbamylase. Administration of growth hormone to hypophysectomized rats brought these enzyme activities back to normal. Since growth hormone plays a role in the formation of citrulline and ultimately urea, in the present study its effect on the levels of N-acetyl-L-glutamate, an allosteric activator of carbamyl phosphate synthetase has been investigated. A significant increase in N-acetyl-L-glutamate concentration in rat liver on hypophysectomy and its reversal back to normal levels on growth hormone administration was reported. These results suggest that the lack of growth hormone tends to amplify urea production by the liver.
早期研究表明，垂体切除术后，线粒体尿素循环酶（即氨甲酰磷酸合成酶和鸟氨酸转氨甲酰酶）会有特定增加。给垂体切除的大鼠注射生长激素可使这些酶的活性恢复正常。由于生长激素在瓜氨酸及最终尿素的形成过程中发挥作用，因此在本研究中，对其对氨甲酰磷酸合成酶的变构激活剂N-乙酰-L-谷氨酸水平的影响进行了研究。据报道，垂体切除术后大鼠肝脏中N-乙酰-L-谷氨酸浓度显著增加，而注射生长激素后其浓度又恢复到正常水平。这些结果表明，生长激素缺乏倾向于增强肝脏的尿素生成。
