Pattern of energy storage in the liver and muscle of rats submitted to total parenteral nutrition

Abstract

TPN was administered to young male rats for 10 days at a low (270 kcal/kg/day) and a high (250 kcal/kg/day) energy level, with an isonitrogenous supply (0.9 g N/kg/day). The non-protein calories were divided into three energy substrate ratios: 0% Fat 100% Glucose , 6% Fat 94% Glucose , and 60% Fat 40% Glucose . Glycogen, acylglycerols and enzyme activities of the heart and some skeletal muscles (tib. anterior, ext. dig. longus and soleus) were unaffected by the various intravenous regimens. The glycogen content of the liver was significantly higher in both low fat groups. There was also a clear tendency in all groups to lower values of glycogen as the energy level of the TPN increased. The opposite trend was seen with acylglycerols, which were highest in the high glucose and high fat groups. The highest acylglycerol content was found in the high fat group at the high energy level. This study demonstrates that unbalanced intravenous regimens, without fat or with a fat overload (20 g/kg/day), seem to alter the storage pattern of glycogen and fat in the liver, particularly when hypercaloric regimens are given. The heart and skeletal muscles seemed to be protected from this effect.