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KMID : 0351619660070020161
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Kyungpook Medical Journal
1966 Volume.7 No. 2 p.161 ~ p.169
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Rates of Biosynthesis of Plasma and Liver Proteins in Perfused Liver of Rats Fed on Low and High Protein Diet.
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Abstract
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The rates of synthesis of plasma and liver proteins on livers of rats raised on low and high protein diets have been determined in the perfused liver by measuring the rates of incorporation of carbon-14 labelled amino acid of known specific activity. The growing rate of liver donor rat fed on low protein diet (5% casein diet) after weaning was 1.6g. per day in average, and rat fed on high protein diet (25% casein diet) was 3.7g. per day in average.
The rate of incorporation of L-Leucine-C^(14) into total plasma protein in the perfused liver of low protein diet rat was 89.1 micro g./hour/g. of wet liver weight in average, into albumin 32.9 micro g. and globulin 56.2 micro g. In high protein diet rat, the incorporation rates into plasma total protein, albumin and globulin were 65.1 micro g., 24.8 micro g. and 40.3 micro g./hour/g. of wet liver weight respectively.
The amount of L-leucine-C^(14) Incorporated into liver protein and free L-leucine concentration in the liver tissue after 7 hours´ perfusion on each group was: in low protein diet rat, into liver protein 595 micro g.／g. of wet liver weight, free L-leucine 92 micro g.／g. of wet liver weight and in high protein diet rat, into liver protein 407 micro g., free L-leucine 97 micro g. (L-leucine concentration in the liver tissue was also calculated by the same specific acivity of L-leucine-C^(14) in the blood).
As shown above, the liver of rat raised on low protein diet produced a significantly higher amount of proteins of plasma and liver than the liver of high protein diet rat. but no noticeable difference was observed in free L-leucine concentration in the liver tissue.
When human blood was used as perfusate in stead of the rat blood, the results showed the same tendency with above results. Incorporation of L-leucine into total plasma protein, in low protein diet group, was 94.7 micro g./hour/g. of wet liver weight and into liver protein was 682 micro g./g. of wet liver weight for 7 hours. In high protein diet group, the rate of incorporation into plasma protein was 59.1 micro g., into liver protein was 414 micro g., and free L-leucine concentration in the liver tissue after 7 hours´ perfusion was 103.6 micro g. and 99.9 micro g./g. of wet liver weight respectively.
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