Muscle starvation state

Many tissues (muscle, liver, renal cortex) prefer fat for an energy supply, at least in the resting state. The exception is red blood cells and brain. These tissues depend heavily on glycolysis for energy. Red cells cannot survive without glucose (no mitochondria), but during prolonged starvation, brain can adapt to utilize fat metabolites produced by the liver (ketone bodies). 

If food is unavailable for more than approximately 24 h, glycogen reserves in the liver will become depleted and the individual would enter a state of biochemical starvation. Progressive loss of muscle protein (wasting) would occur in order to generate sufficient glucose to maintain the metabolic activity of, in particular, the central nervous system. 

Ketones themselves may be used as fuel. The brain, which normally prefers glucose, can use ketones in states of starvation. Cardiac muscle commonly uses ketones as fuel. 

There is a large increase in urine zinc whenever there is accelerated breakdown of skeletal muscle and other tissue. After injury or in acute starvation the rise in urinary zinc is evidence of a catabolic state (Fell et al., 1973). 

Short-term starvation in rainbow trout results in a reduction in the rates of synthesis of the whole muscles and the individual fractions and a decrease in the cytochrome oxidase activity (unpubl. results). In a similar manner, rates of synthesis of mammalian myofibrils have been found to be markedly sensitive to nutrition (Bates and Millward 1983). There have been a number of papers which have shown a correlation between the nutritional state of fish and the levels of glycolytic and oxidative enzymes (Sullivan and Somero 1983 Goolish and Adel-man 1987) and it will be of interest to correlate plane of nutrition, whole muscle and mitochondrial protein synthesis and enzyme activities. The correlation between RN A concentration and protein synthesis rates discussed below suggests that we are witnessing a number of nutritionally controlled parameters which are operating in concert increasing, for example, the aerobic scope of the tissues and their scope for protein synthesis. 

The pathophysiology of starvation in anorexia nervosa is obscure. Basal metabolism has been found to be reduced, probably due to the decrease in cell mass of the body. Atrofic changes in. skeletal muscle and adipose tissue have been observed, otherwise no information is available about the metabolic state of different tissues. 

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