TY - JOUR
T1 - L-ornithine-L-aspartate lowers plasma and cerebrospinal fluid ammonia and prevents brain edema in rats with acute liver failure
AU - Rose, Christopher
AU - Michalak, Adrianna
AU - Rao, K. V.Rama
AU - Quack, Günter
AU - Kircheis, Gerald
AU - Butterworth, Roger F.
N1 - Copyright:
Copyright 2007 Elsevier B.V., All rights reserved.
PY - 1999
Y1 - 1999
N2 - Brain edema sufficient to cause intracranial hypertension and brain herniation remains a major cause of mortality in acute liver failure (ALF). Studies in experimental animal models of ALF suggest a role for ammonia in the pathogenesis of both encephalopathy and brain edema in this condition. As part of a series of studies to evaluate the therapeutic efficacy of ammonia- lowering agents, groups of rats with ALF caused by hepatic devascularization were treated with L-ornithine-L-aspartate (OA), an agent shown previously to be effective in reducing blood ammonia concentrations in both experimental and human chronic liver failure. Treatment of rats in ALF with infusions of OA (0.33 g/kg/h, intravenously) resulted in normalization of plasma ammonia concentrations and in a significant delay in onset of severe encephalopathy. More importantly, brain water content was significantly reduced in OA-treated rats with ALF. These protective effects of OA were accompanied by increased plasma concentrations of several amino acids including glutamate, γ- aminobutyric acid (GABA), taurine, and alanine, as well as the branched-chain amino acids, leucine, isoleucine, and valine, increased availability of glutamate following OA treatment provides the substrate for the major ammonia-removal mechanism (glutamine synthetase). Plasma (but not cerebrospinal fluid) glutamine concentrations were increased 2-fold (P < .02) in OA-treated rats, consistent with increased muscle glutamine synthesis. Direct measurement of glutamine synthetase activities revealed a 2-fold increase following OA treatment. These findings demonstrate a significant ammonia-lowering effect of OA together with a protective effect on the development of encephalopathy and brain edema in this model of ALF.
AB - Brain edema sufficient to cause intracranial hypertension and brain herniation remains a major cause of mortality in acute liver failure (ALF). Studies in experimental animal models of ALF suggest a role for ammonia in the pathogenesis of both encephalopathy and brain edema in this condition. As part of a series of studies to evaluate the therapeutic efficacy of ammonia- lowering agents, groups of rats with ALF caused by hepatic devascularization were treated with L-ornithine-L-aspartate (OA), an agent shown previously to be effective in reducing blood ammonia concentrations in both experimental and human chronic liver failure. Treatment of rats in ALF with infusions of OA (0.33 g/kg/h, intravenously) resulted in normalization of plasma ammonia concentrations and in a significant delay in onset of severe encephalopathy. More importantly, brain water content was significantly reduced in OA-treated rats with ALF. These protective effects of OA were accompanied by increased plasma concentrations of several amino acids including glutamate, γ- aminobutyric acid (GABA), taurine, and alanine, as well as the branched-chain amino acids, leucine, isoleucine, and valine, increased availability of glutamate following OA treatment provides the substrate for the major ammonia-removal mechanism (glutamine synthetase). Plasma (but not cerebrospinal fluid) glutamine concentrations were increased 2-fold (P < .02) in OA-treated rats, consistent with increased muscle glutamine synthesis. Direct measurement of glutamine synthetase activities revealed a 2-fold increase following OA treatment. These findings demonstrate a significant ammonia-lowering effect of OA together with a protective effect on the development of encephalopathy and brain edema in this model of ALF.
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U2 - 10.1002/hep.510300311
DO - 10.1002/hep.510300311
M3 - Article
C2 - 10462368
AN - SCOPUS:0032868948
SN - 0270-9139
VL - 30
SP - 636
EP - 640
JO - Hepatology
JF - Hepatology
IS - 3
ER -