Leucine and phenylalanine kinetics during mixed meal ingestion: a multiple tracer approach.

摘要: To estimate whole body and splanchnic metabolism of dietary amino acids, phenylalanine leucine kinetics were determined simultaneously in six normal volunteers before during the constant administration a complete mixed meal, employing multiple tracers these acids. L-[5,5,5-2H]leucine L-[2,6-3H]-phenylalanine infused intravenously; L-[1-13C]leucine L-[1-14C]phenylalanine administered orally with meal. During steady-state concentration rose from 136 +/- 6 to 190 14 mumol/l (P less than 0.01), 44 4 61 total rate appearance (Ra) 1.29 0.03 1.77 0.07 0.01, +37 3%), Ra 0.73 0.05 0.80 mumol.kg-1.min-1 0.05, +8 3%). Splanchnic uptake was greater 0.001) that (58 vs. 25 4%, respectively), 3% circulating derived diet 20 2% 0.01). Endogenous significantly suppressed 0.05). In summary: 1) is onefold leucine; 2) contribution systemic about half Ra; 3) endogenous both after meal suppressed. conclusion, differs markedly can be quantitated vivo without catheterization.