At the end of each treatment phase , fasted subjects received a 10 mol/L per kg bolus injection of [ 5,5,5 - ( 2 ) H3 ] - l-Leucine immediately followed by constant infusion of [ 5,5,5 - ( 2 ) H3 ] - l-Leucine ( 10 mol L ( -1 ) kg ( -1 ) h ( -1 ) ) for 14 hours , and blood samples were collected .