Age-related changes in muscle ammonia detoxification potential in exhausted rats.

The changes in the pattern of production and detoxification of ammonia have been studied in the skeletal muscles and blood of rats of different age groups (1, 3, 6, 12 and 24 months), subjected to exhaustive exercise. The protein profiles at exhaustion showed a sharp drop in all muscles and the decrement was more in the senile rats. In general, the muscle and blood ammonia content increased with age with a corresponding increase in AMP deaminase activity implicating the possibility of elevated purine nucleotide deamination during senescence. However, glutamate oxidation was decreased and urea and glutamine formation was increased consequent to ammonia production during senescence under intensive physical stress. The possible alterations in protein levels and ammonia production and its disposal in different skeletal muscle types of senile exhausted rats have been discussed in relation to detoxication capacity of the fibre types.