Total body protein catabolism in starved and infected rats

The catabolic effects of starvation alone, or starvation in the presence of pneumococcal sepsis, were compared in rats whose skeletal muscle protein had been tagged 14 days earlier with 14C-phenylalanine. In a fed rat, protein catabolism (as estimated by expired 14CO2) is not constant throughout the day but is highest during the dark hours. Starvation is associated with accelerated protein catabolism and a gradual loss of periodicity. Infection increases the rate of catabolism still further and results in a complete loss of periodicity.