Muscle wasting in emphysema.
1. We have investigated arteriovenous exchanges of tyrosine and 3-methylhistidine across leg tissue in the postabsorptive state as specific indicators of net protein balance and myofibrillar protein breakdown, respectively, in eight patients with emphysema and in 11 healthy controls. Whole-body protein turnover was measured using L-[1-13C]leucine. 2. Leg efflux of tyrosine was increased by 47% in emphysematous patients compared with normal control subjects, but 3-methylhistidine efflux was not significantly altered. 3. In emphysema, whole-body leucine flux was normal, whole-body leucine oxidation was increased, and whole-body protein synthesis was depressed. 4. These results indicate that the predominant mechanism of muscle wasting in emphysema is a fall in muscle protein synthesis, which is accompanied by an overall fall in whole-body protein turnover.
Morrison
W L
WL
Department of Physiology, University of Dundee, U.K.
Gibson
J N
JN
Scrimgeour
C
C
Rennie
M J
MJ
D000328:Adult; D000368:Aged; D000596:Amino Acids / Q000378:metabolism; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight; D006801:Humans; D007773:Lactates / Q000378:metabolism; D007866:Leg; D007930:Leucine / Q000378:metabolism; D008762:Methylhistidines / Q000378:metabolism; D008875:Middle Aged; D009124:Muscle Proteins / Q000378:metabolism*; D009210:Myofibrils / Q000378:metabolism; D010101:Oxygen Consumption; D011506:Proteins / Q000378:metabolism; D011656:Pulmonary Emphysema / Q000378:metabolism*; D012129:Respiratory Function Tests; D012885:Skinfold Thickness; D014443:Tyrosine / Q000378:metabolism
D000596:Amino Acids; D001786:Blood Glucose; D007773:Lactates; D008762:Methylhistidines; D009124:Muscle Proteins; D011506:Proteins; D014443:Tyrosine; D007930:Leucine; C028118:3-methylhistidine