Which of the following amino acid is extracted predominantly by muscle, having been spared by the liver in postprandial state?

After a protein rich meal, splanchnic tissues (stomach, small intestine, large intestine, pancreas, spleen and liver,) release branched chain amino acids (valine, leucine & isoleucine) & they are mainly extracted by peripheral tissues like skeletal muscles. The branched chain amino acid released by liver are mainly taken up by skeletal muscles (see fig) During fasting state, these branched chain amino acids stores of muscles are transpoed to provide energy to brain. valine is most commonly transpoed to brain. Therefore, branched chain amino acids have a special role in nitrogen metabolism. Free amino acid Alanine is transpoed from muscles to liver after feeding. During fasting state also, exchange of alanine happens between liver and muscles in glucose-alanine cycle (Cahill cycle).