Hepatic amino acid and protein metabolism in non-anorectic, moderately cachectic tumor-bearing rats

Background/Aims: Cancer cachexia is characterized by loss of lean body mass. Under this condition peripheral proteins are broken down and transferred to visceral organs and the tumor. The liver is the principal organ in the regulation of protein and amino acid metabolism, but liver amino acid kinetics in cancer are unclear. Therefore, we examined the effects of increasing tumor loads on hepatic protein turnover and amino acid handling. Methods: A MCA-induced sarcoma was implanted subcutaneously in Lewis rats (200–225 g). Rats were studied when the tumor was 5–15% or 15–30% of body weight. Control rats were sham implanted. Under anesthesia, a primed constant infusion of para-aminohippuric acid and L-[3,4- 3H]-valine was given to calculate hepatic substrate fluxes and protein turnover. Serum α 2-macroglobulin concentration was measured to determine the acute phase response. Results: Carcass weight decreased approximately 10% in large-tumor-bearing rats ( p