Protein synthesis, cellular amino acids, and energy levels in CAPD patients.

Cellular energy-related bioactivities [energy charge = ATP + 0.5 ADP/(ATP + ADP + AMP)], enzyme activities adenylate kinase, pyruvate kinase, phosphofructokinase, glucose-6-phosphate dehydrogenase, free amino acids in plasma and cells, and protein synthesis (3H-leucine incorporation) were measured in granulocytes isolated from peripheral blood of 13 CAPD-treated adult patients. The values were compared with 37 normal adult controls, 29 of whom had complete data for all biochemical parameters. Eleven of the CAPD patients were studied a second time, 3 to 8 months after the first study. Initially, after 20 +/- 8 months of CAPD compared (P less than 0.05, only) to controls, the patients had normal or increased activities of the enzymes pyruvate kinase, phosphofructokinase, glucose-6-phosphate dehydrogenase, in contrast to previous results from hemodialyzed patients; but adenylate kinase, ATP, and protein synthesis were reduced. Concentrations of many amino acids in plasma were abnormal, including reduced valine, leucine, threonine, tryptophan, and tyrosine, as noted by others. Histidine, glutamic acid, and citrulline especially were increased. The intracellular concentrations of the essential amino acids were within normal limits, but citrulline, glycine, and taurine levels were markedly increased while glutamic acid and SAGN (serine + asparagine + glutamine) were decreased. With the second study, intracellular energy-related bioactivities and the abnormal concentrations of the amino acids in plasma were essentially unchanged. However, virtually all the intracellular amino acid concentrations were higher. These results also were in striking contrast to previously reported hemodialysis patients in whom the intracellular concentrations of the branched-chain amino acids and methionine as well as protein synthesis were strikingly decreased.(ABSTRACT TRUNCATED AT 250 WORDS)