ALBUMIN SYNTHESIS AFTER INTENSE INTERMITTENT EXERCISE IN HUMAN-SUBJECTS

We measured hepatic albumin synthesis in five volunteers (4 men and 1 woman) at 3 and 6 h after recovery from intense exercise. A primed-con stant infusion of a stable isotopic tracer of phenylalanine was used t o determine hepatic fractional synthetic rate (FSR) and absolute synth etic rate (ASR) of albumin from the enrichment of phenylalanine in alb umin. The infusion of the stable isotope tracer began 2 h after uprigh t exercise or upright rest. Albumin FSR and ASR were 6.39 +/- 0.48%/da y and 120 +/- 9 mg.kg body wt(-1).day(-1), respectively, 3-6 h after r ecovery from exercise; the FSR and ASR on the time control study day w ere 5.94 +/- 0.47%/day and 104 +/- 9 mg.kg body wt(-1).day(-1), respec tively. The 6 and 16% increases (P < 0.05) in FSR and ASR after exerci se were associated with an elevated plasma albumin content at 5 and 6 h of recovery (P < 0.05), an increased total protein content throughou t recovery (P < 0.05), and a negative free water clearance (P < 0.05) at 2, 3, and 6.5 h of recovery compared with baseline values; these va riables were unchanged from their baselines on the time control study day. Increased albumin content and reduced free water clearance contri bute to a retention of fluid within the circulation after intense exer cise. The measured increase in albumin synthesis could not account for the entire increase in albumin content at 6 h of recovery from exerci se. However, we estimate that if the increased activity was maintained for the next 18 h, it could account for the expected increase in albu min content at 24 h of recovery.