![]() |
|
|
Department of Nutrition and Food Science, Massachusetts Institute of Technology, Cambridge, Massachusetts
The effect of Salmonella typhimurium infection on protein metabolism in the skeletal muscle of the hind leg was studied in rats in 2 experiments. In experiment 1 rats were fed an adequate-protein diet and killed at zero, 1, 2, 3, and 5 days after infection. In vivo uptake of 14C-leucine by muscle ribosomes into nascent peptides was measured; and ribosomes were studied by sucrose gradient analysis. Infection reduced the uptake of radioactivity by ribosomes and resulted in lowered levels of heavy polyribosomes and increased proportions of the light ribosome species. In experiment 2 weanling rats were prefed a low protein or adequate-protein diet for 9 days and then infected. In vivo and in vitro synthetic capacity of muscle ribosomes was studied at zero, 1, 2, 3, or 7 days after infection. The in vivo and in vitro protein-synthesizing capacity of the ribosomes was reduced by the infection in both dietary groups. Clear-cut differences in the variables studied were not observed between the dietary groups during the first 3 days after infection. The changes are discussed in relation to the metabolic nitrogen loss occurring during infection.
2 This is contribution no. 1151 from the Department of Nutrition and Food Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139.
3 Present address: Market Quality Research Division, U.S. Department of Agriculture, Beltsville, Maryland.
Manuscript received 16 October 1967.