DERANGEMENT IN AEROBIC AND ANAEROBIC ENERGY-METABOLISM IN SKELETAL-MUSCLE OF CRITICALLY ILL AND RECOVERING RATS

As part of our research into the mechanisms of protein wasting and mus cle weakness during critical illness, we here investigate various aspe cts of energy metabolism. Intraperitoneal injection of zymosan in rats leads to an acute phase of critical illness followed by a prolonged r ecovery phase. Previously we observed low activities of mitochondrial enzymes, reduced protein synthesis rates and low concentrations of glu tamine in skeletal muscle of zymosan-treated rats, In the present stud y we investigated (1) whether decreases in high energy phosphates are present in skeletal muscle of these rats and (2) whether an impairment in the glycolytic pathway or the tricarboxylic acid cycle leads to th ese decreases, Concentrations of creatine phosphate and ATP were decre ased in zymosan-treated rats to approx. 85% of pair-fed control values respectively on day 2 and on days 4 and 6 after treatment, Concentrat ions of tricarboxylic acid (TCA) cycle intermediates were decreased to 80% on day 6 after zymosan treatment. Lactate/pyruvate ratio and conc entrations of lactate and glycogen were normal at all sampling times, We conclude that no major changes in concentrations of high energy pho sphates and in concentrations of intermediates of TCA cycle, glycolysi s and glycogenolysis were present. This indicated that, although the m aximal oxidative capacity (mitochondrial content) is decreased, no der angement in energy metabolism seems to be present in skeletal muscle o f critically ill and recovering rats.