Comparison of Human Myofibrillar Protein Catabolic Rate Derived from 3-Methylhistidine Excretion with Synthetic Rate from Muscle Biopsies during l-[α-15N]Lysine Infusion
- 1 May 1978
- journal article
- research article
- Published by Portland Press Ltd. in Clinical Science
- Vol. 54 (5) , 471-475
- https://doi.org/10.1042/cs0540471
Abstract
1. Urine was collected in five healthy men over 10–14 days, with fasting blood samples on days 1, 5 and 10, whilst they consumed a standard creatine-free diet, which was quantitatively related to their body surface area. 2. The urinary excretion of 3-methylhistidine fell to a plateau by day 5 in all subjects. Myofibrillar protein catabolic rate calculated from the mean value of 3-methylhistidine excretion from day 5 to day 10 averaged 1·21 g day−1 kg−1 body weight. The average turnover of muscle myofibrillar protein was calculated to be 2·16%/day. 3. From a previous study using continuous intravenous infusion of l-[α-15N]lysine with serial muscle biopsies on the same subjects, the mean myofibrillar protein synthetic rate was calculated to be 0·82 g day−1 kg−1 body weight, and the mean turnover rate was 1·47%/day of total muscle myofibrillar protein. 4. The estimations of myofibrillar protein turnover rate derived from the two methods are compared and the differences discussed.Keywords
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