Ammonia toxicity and cerebral oxidative metabolism.
نویسندگان
چکیده
Ammonia toxicity and cerebral oxidative metabolism. Am. J. Physiol. 200(3) : 420-424. 1961. -Effects of NH&l on oxidative metabolism of cat cerebral cortex slices and mitochondria incubated in vitro were studied. In slices, addition of IO mM NH&l to the incubation medium resulted in significant (16%) reduction of O2 uptake, doubling of lactic acid production and marked increase of glucose utilization compared to control slices. Mitochondria showed a 30-407~ decrease of O2 consumption in the presence of I 5 mM NH&l when pyruvate or a-ketoglutarate were substrates, but little if any difference from controls with succinate, glutamic acid or y-aminobutyric acid as substrates. Pyruvate utilization by ammonia-treated mitochondria was inhibited to the same degree as O2 consumption and was not increased by supplementing the incubation medium with excess succinate. Additions of &ipoic acid, thiamine pyrophosphate or DPN to such preparations failed to reverse the NH&l effect. Satisfactory P/O ratios were obtained for all mitochondrial preparations. It is concluded that a primary toxic effect of ammonia on the brain may be direct interference with oxidative decarboxylation of pyruvic and a-ketoglutaric acids.
منابع مشابه
Resveratrol Prevents Ammonia Toxicity in Astroglial Cells
Ammonia is implicated as a neurotoxin in brain metabolic disorders associated with hyperammonemia. Acute ammonia toxicity can be mediated by an excitotoxic mechanism, oxidative stress and nitric oxide (NO) production. Astrocytes interact with neurons, providing metabolic support and protecting against oxidative stress and excitotoxicity. Astrocytes also convert excess ammonia and glutamate into...
متن کاملThe effect of hyperventilation upon cerebral blood flow and metabolism in patients with fulminant hepatic failure.
Patients with FHF have a high risk of cerebral edema and intracranial hypertension. The pathophysiological background for this phenomenon is not completely settled, but alteration in CBF as well as cerebral metabolism seems to be of importance. Mechanical hyperventilation has a prompt effect on intracranial pressure. This effect is assumed to be caused by the hypocapnia induced alkalosis which ...
متن کاملAmmonia intoxication in portal systemic encephalopathy.
Portal systemic encephalopathy (PSE) comprises of five major features, of which ammonia intoxication of the central nervous system is the only specific feature. Ammonia is a key intermediate in the metabolism of nitrogen. Oxidative deamination of aminoacids is one of the major ammonia producing pathways. It occurs predominantly in the liver, to a lesser extent kidneys and also in the brain. The...
متن کاملImpact of Ammonia on Oxidative Metabolism in Certain Tissues of Albino Rat
Ammonia has received increasing attention over the past few years as a potentially important pollutant. The metabolic changes and potentialities of ammonia in high concentration are reported in all groups of animals as ammonia toxicity and stress. However, at high levels, ammonia is toxic, leading to functional disturbances of the central nervous system that can lead to coma and death. The pres...
متن کاملOxidative metabolism of astrocytes is not reduced in hepatic encephalopathy: a PET study with [11C]acetate in humans
In patients with impaired liver function and hepatic encephalopathy (HE), consistent elevations of blood ammonia concentration suggest a crucial role in the pathogenesis of HE. Ammonia and acetate are metabolized in brain both primarily in astrocytes. Here, we used dynamic [(11)C]acetate PET of the brain to measure the contribution of astrocytes to the previously observed reduction of brain oxi...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- The American journal of physiology
دوره 200 شماره
صفحات -
تاریخ انتشار 1961