Liver protein and glutamine metabolism during cachexia

The word cachexia is derived from the Greek words ‘kakos’ and ‘hexis’ meaning poor condition or bad health. This syndrome indicates a state of wasting of primarily peripheral (muscle) tissues in the presence of a variety of diseases, such as cancer, acquired immune deficiency syndrome or tuberculosis, in which the host’s inflammatory response plays an important role. This wasting results in loss of cell mass from the body. An important distinction exists, however, between depletion of body cell mass due to pure starvation, and depletion which is caused by the combined presence of starvation and disease, or more specifically a severe or prolonged inflammatory response. This latter category is referred to as cachexia and is the condition most frequently found in patient populations. One of the major differences is the fact that during pure starvation visceral organs such as the liver and the gut break down protein furnish substrate for host protein metabolism while muscle protein is preserved at first & McManus, 1985). Furthermore, protein synthesis rates and protein turnover are down regulated resulting in decreased N losses. In cachectic patients, on the other hand, starvation is usually accompanied by inflammation and muscle protein is broken down, leading to net release of amino acids which subsequently are taken up by viscera like the liver and spleen. Furthermore, N losses are significantly larger than during pure starvation.