Time course of change in respiratory quotient during prolonged starvation in carbon tetrachloride-induced cirrhotic rats

To assess the metabolic response to prolonged fasting in cirrhosis, time courses of glucose and fuel metabolism were characterized in rats with carbon tetrachloride (CCl4)-induced cirrhosis. After 10 hour starvation, glycogen concentration in the liver was significantly lower in the cirrhotic rats than in the normal rats, although blood glucose levels were stable during starvation in both rats. Accumulation of orally administered D-(U-C-14) glucose in muscle and fatty tissue was not significantly different between normal and cirrhotic rats after prolonged starvation, but those of liver and plasma was significantly lower in the cirrhotic rats, suggesting that orally administered glucose was consumed mostly by peripheral tissues in the cirrhotic rats. In the cirrhotic rats, fat utilization progressively increased with time during prolonged fasting, indicated by low respiratory quotient (RQ) and increased fasting blood levels of free fatty acid. In contrast, the RQ of the normal rats remains relatively stable after 6 hours of fasting, suggesting that liver can produce glucose constantly after 6 hours in the normal rats. The supplementation of branched chain amino acid-mixture (Aminoleban EN R) as well as glucose increased glycogen concentration in the liver and blood glucose levels. The RQ increased initially by supplementation, but then decreased progressively in the cirrhotic rats. The speed of decrease in RQ was not significantly altered by supplementation, suggesting that only way to improve the catabolic states might be frequent feeding to shorten the duration of fasting. (C) 2002 Elsevier Science Inc. All rights reserved.