53 research outputs found
Alterations of Blood Brain Barrier Function in Hyperammonemia: An Overview
Ammonia is a neurotoxin involved in the pathogenesis of neurological conditions associated with hyperammonemia, including hepatic encephalopathy, a condition associated with acute—(ALF) or chronic liver failure. This article reviews evidence that apart from directly affecting the metabolism and function of the central nervous system cells, ammonia influences the passage of different molecules across the blood brain barrier (BBB). A brief description is provided of the tight junctions, which couple adjacent cerebral capillary endothelial cells to each other to form the barrier. Ammonia modulates the transcellular passage of low-to medium-size molecules, by affecting their carriers located at the BBB. Ammonia induces interrelated aberrations of the transport of the large neutral amino acids and aromatic amino acids (AAA), whose influx is augmented by exchange with glutamine produced in the course of ammonia detoxification, and maybe also modulated by the extracellularly acting gamma-glutamyl moiety transferring enzyme, gamma-glutamyl-transpeptidase. Impaired AAA transport affects neurotransmission by altering intracerebral synthesis of catecholamines (serotonin and dopamine), and producing “false neurotransmitters” (octopamine and phenylethylamine). Ammonia also modulates BBB transport of the cationic amino acids: the nitric oxide precursor, arginine, and ornithine, which is an ammonia trap, and affects the transport of energy metabolites glucose and creatine. Moreover, ammonia acting either directly or in synergy with liver injury-derived inflammatory cytokines also evokes subtle increases of the transcellular passage of molecules of different size (BBB “leakage”), which appears to be responsible for the vasogenic component of cerebral edema associated with ALF
Citrulline uptake in rat cerebral cortex slices: Modulation by Thioacetamide -Induced hepatic failure
Cortical Synaptic Transmission and Plasticity in Acute Liver Failure Are Decreased by Presynaptic Events
Roles of Changes in Active Glutamine Transport in Brain Edema Development During Hepatic Encephalopathy: An Emerging Concept
Changes of the Thioredoxin System, Glutathione Peroxidase Activity and Total Antioxidant Capacity in Rat Brain Cortex During Acute Liver Failure: Modulation by l-histidine
Carnosine Reduces Oxidative Stress and Reverses Attenuation of Righting and Postural Reflexes in Rats with Thioacetamide-Induced Liver Failure
Effect of Alkalinisation of Lignocaine for Propofol Injection Pain: A Prospective, Randomised, Double-Blind Study
Alkalinisation of Local Anaesthetics Prescribed for Pain Relief after Surgical Decompression of Carpal Tunnel Syndrome
Comparison of two different techniques for brachial plexus block: infraclavicular versus axillary technique
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