Summary.
Three models representing different separations of amino acid sources were used to simulate experimental specific radioactivity data and to predict protein fractional synthesis rate (FSR). Data were from a pulse dose of 14C-U Leu given to a non-growing 20 g mouse and a flooding dose of 3H Phe given to a non-growing 200 g rat. Protein synthesis rates estimated using the combined extracellular and intracellular (Ec + Ic) source pool and extracellular and plasma (Ec + Pls) source pool mouse models were 78 and 120% d−1 in liver, 14 and 16% d−1 in brain and 15 and 14% d−1 in muscle. Predicted protein synthesis rates using the Ec + Ic, Ec + Ic + Tr (combined extracellular, intracellular and aminoacyl tRNA source pool) and Ec + Pls rat models were 57, 3.4 and 57% d−1 in gastrocnemius, 58, 71 and 62% d−1 in gut, 8.3, 8.4 and 7.9% d−1 in heart, 32, 23 and 25% d−1 in kidney, 160, 90 and 80% d−1 in liver, 57, 5.5 and 57% d−1 in soleus and 56, 3.4 and 57% d−1 in tibialis. The Ec + Ic + Tr model underestimated protein synthesis rates in mouse tissues (5.0, 27 and 2.5% d−1 for brain, liver and muscle) and rat muscles (3.4, 5.5 and 3.4% d−1 for gastrocnemius, soleus and tibialis). The Ec + Pls model predicted the mouse pulse dose data best and the Ec + Ic model predicted the rat flooding dose data best. Model predictions of FSR imply that identification and separation of the source specific radioactivity is critical to accurately estimate FSR.
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Received June 11, 2000 Accepted September 26, 2000
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Johnson, H., Baldwin, R., Klasing, K. et al. Impact of separating amino acids between plasma, extracellular and intracellular compartments on estimating protein synthesis in rodents. Amino Acids 20, 389–400 (2001). https://doi.org/10.1007/s007260170035
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DOI: https://doi.org/10.1007/s007260170035