Total and net muscle protein breakdown in infection determined by amino acid effluxes.
The present investigation was undertaken to study whether, in human infection of varying severity, peripheral 3-methylhistidine efflux and urinary excretion are associated with net protein degradation and to estimate the protein synthesis rate from the combined effluxes of 3-methylhistidine, tyrosine, and phenylalanine. Quadruplicate femoral arteriovenous differences of 3-methylhistidine, tyrosine, and phenylalanine were multiplied by leg plasma flow in 15 infected patients. Leg effluxes for 3-methylhistidine, tyrosine, and phenylalanine were -0.074 +/- 0.011, -2.57 +/- 0.43, and -3.17 +/- 0.44 mumol/min, respectively. There was a significant linear relationship (P less than 0.01) between the effluxes of tyrosine and phenylalanine and the efflux and urinary excretion of 3-methylhistidine. A significant release of tyrosine and phenylalanine was observed in patients studied at the 3-methylhistidine level seen in normal healthy subjects. It is concluded that in infection 1) there is an increased breakdown of skeletal muscle protein and a reduced rate of protein synthesis, with the latter being relatively more important in patients with mild disease; and 2) urinary 3-methylhistidine excretion is associated with net skeletal muscle protein degradation for the patient group studied.
Sjölin
J
J
Department of Infectious Diseases, University Hospital, Uppsala, Sweden.
Stjernström
H
H
Friman
G
G
Larsson
J
J
Wahren
J
J
D000005:Abdomen; D000038:Abscess / Q000378:metabolism; D000328:Adult; D000596:Amino Acids / Q000097:blood*; D001424:Bacterial Infections / Q000209:etiology / Q000378:metabolism*; D002056:Burns / Q000150:complications; D005260:Female; D006801:Humans; D007866:Leg; D008297:Male; D008762:Methylhistidines / Q000652:urine; D009124:Muscle Proteins / Q000378:metabolism*; D009132:Muscles / Q000378:metabolism*; D011704:Pyelonephritis / Q000378:metabolism
D000596:Amino Acids; D008762:Methylhistidines; D009124:Muscle Proteins; C028118:3-methylhistidine