Intense exercise stimulates albumin synthesis in the upright posture

We tested the hypothesis that an elevation in albumin synthetic rate contri butes to increased plasma albumin content during exercise-induced hypervole mia. Albumin synthetic rate was measured in seven healthy subjects at 1-5 a nd 21-22 h after 72 min of intense (85% peak oxygen consumption rate) inter mittent exercise and after 5 h recovery in either upright (Up) or supine (S up) postures. Deuterated phenylalanine (d(5)-Phe) was administrated by a pr imed-constant infusion method, and fractional synthetic rate (FSR) and abso lute synthetic rate (ASR) of albumin were calculated from the enrichment of dB-Phe in plasma albumin, determined by gas chromatography-mass spectromet ry. FSR of albumin in Up increased significantly (P < 0.05) from 4.9 +/- 0. 9%/day at control to 7.3 +/- 0.9%/day at 22 h of recovery. ASR of albumin i ncreased from 87.9 +/- 17.0 to 141.1 +/- 16.6 mg albumin . kg body wt(-1) . day(-1). In contrast, FSR and ASR of albumin were unchanged in Sup (3.9 +/ - 0.4 to 4.0 +/- 1.4%/day and 74.2 +/- 8.9 to 85.3 +/- 23.9 mg albumin . kg body wt(-1) . day(-1) at control and 22 h of recovery, respectively). Incr eased albumin synthesis after upright intense exercise contributes to the e xpansion of greater albumin content and its maintenance. We conclude that s timuli related to posture are critical in modulating the drive for albumin synthesis after intense exercise.