Effects of Increased Blood Ammonia Concentrations on the Concentrations of Some Metabolites in Rat Tissues

Abstract

SUMMARYRats were given ammonium chloride intravenously (5 and 10 mg per 100 g body weight) and sacrificed 30 sec, 5 min and 30 min after injection. Ammonia concentrations were determined in brain, liver, skeletal muscle and epididymial fat, and glycogen, glucose, pyruvate, lactate, ATP and cyclic AMP were assayed in brain, liver and muscle. In control animals, muscle and fat showed a high capacity for ammonia accumulation. After injection of NH4C1 the ammonia concentration increased in all tissues analysed, particularly in muscle and fat, where ammonia concentrations remained elevated for 30 min. In brain, glycogen was reduced whereas glucose, pyruvate, lactate and cyclic AMP levels were raised. In liver, glycogen was lower and glucose higher than in controls. ATP concentrations were unchanged in both tissues. In muscle samples taken 30 sec and 5 min after dosing, glycogen concentrations were not affected but glucose, pyruvate and lactate concentrations were reduced and ATP concentrations were increased. In muscle samples taken after 30 min metabolite concentrations were normal again but glycogen concentrations had dropped.

Muscle Amino Acid and Adenine Nucleotide Metabolism during Exercise and in Liver Cirrhosis: Speculations on How to Reduce the Harmful Effects of Ammonia

“…In a healthy individual, there is no significant net uptake or release of ammonia by muscles in a state of inactivity although ammonia concentration in muscles is higher than in the blood [ 13 , 14 , 15 ]. This phenomenon has two reasons.…”

Influence of plasma macronutrient levels on hepatic metabolism: role of regulatory networks in homeostasis and disease states

“…Therefore, the nitrogen part of the carbon backbone of the amino acids was liberated as ammonia which was disposed through urea cycle. 70 With increasing glucose levels the potential of urea cycle decreased due to reduction in gluconeogenic ux by insulin and utilization of amino acids for protein synthesis. Moreover, with increasing fatty acid levels, the levels of ammonia rose with increasing amino acids due to reduction in the urea cycle ux.…”