CEREBRAL AMMONIA METABOLISM IN HYPERAMMONEMIC RATS
CEREBRAL AMMONIA METABOLISM IN HYPERAMMONEMIC RATS
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DOI：
10.1111/j.1471-4159.1985.tb07159.x
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发表时间：
1985-01-01
影响因子：
4.7
通讯作者：
GELBARD, AS
中科院分区：
文献类型：
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作者：
COOPER, AJL;MORA, SN;GELBARD, AS
在慢性（门腔静脉分流8周或14周的大鼠）或急性（脲酶处理）高氨血症大鼠的大脑中，测定了血源性[13N]氨的短期代谢去向。利用冷冻吹气技术表明，在正常、慢性高氨血症和急性高氨血症大鼠大脑中，血源性[13N]氨代谢的主要途径是掺入谷氨酰胺（胺）。高氨血症大鼠大脑中[13N]氨转化为L - [酰胺 - 13N]谷氨酰胺的周转率比正常大鼠大脑慢。还测定了14周门腔静脉分流大鼠大脑中几种参与脑氨和谷氨酸代谢的酶的活性。大鼠大脑似乎几乎没有适应慢性高氨血症的能力，因为与体重匹配的对照组相比，参与谷氨酸/氨代谢的以下脑酶的活性没有差异：谷氨酰胺合成酶、谷氨酸脱氢酶、天冬氨酸氨基转移酶、谷氨酰胺转氨酶、谷氨酰胺酶和谷氨酸脱羧酶。结合多种疾病中高氨水平对中枢神经系统的已知有害影响，对研究结果进行了讨论。
The short-term metabolic fate of blood-borne [13N]ammonia was determined in the brains of chronically (8- or 14-wk portacaval-shunted rats) or acutely (urease-treated) hyperammonemic rats. Using a freeze-blowing technique it was shown that the overwhelming route for metabolism of blood-borne [13N]ammonia in normal, chronically hyperammonemic and acutely hyperammonemic rat brain was incorporation into glutamine (amine). The rate of turnover of [13N]ammonia to L-[amide-13N]glutamine was slower in the hyperammonemic rat brain than in the normal rat brain. The activities of several enzymes involved in cerebral ammonia and glutamate metabolism were also measured in the brains of 14-wk portacaval-shunted rats. The rat brain appears to have little capacity to adapt to chronic hyperammonemia because there were no differences in activity compared with those of weight-matched controls for the following brain enzymes involved in glutamate/ammonia metabolism: glutamine synthetase, glutamate dehydrogenase, aspartate aminotransferase, glutamine transaminase, glutaminase and glutamate decarboxylase. The findings are discussed in the context of the known deleterious effects on the CNS of high ammonia levels in a variety of diseases.