Acute Stimulation of Albumin Synthesis Rate with Oral Meal Feeding in Healthy Subjects Measured with [Ring-2H5]Phenylalanine

The short-term effect of oral feeding on albumin synthesis rate was investigated in 12 healthy volunteers using two meal regimens. Albumin synthesis was measured over 90 min after injection of a 'flooding' amount (43 mg/kg body weight) of phenylalanine enriched to 7.5, 10 or 15 atoms % with the stable isotope [ring-2H5]phenylalanine. 2. In one set of subjects, consumption of five small hourly meals resulted in a consistent and significant increase (P < 0.05) in albumin fractional synthesis rate from a mean (+/- SEM) fasting value of 5.8 (+/- 0.4)%/day to 7.1 (+/- 0.4)%/day in the fed state. 3. A second study in which albumin synthesis was measured 30 min after consumption of a single larger meal was carried out in another set of volunteers. The fractional rate of albumin synthesis was again significantly elevated after feeding (P < 0.05), rising from 7.1 (+/- 0.4)%/day in the fasted state to 9.1 (+/- 0.6)%/day in the fed state. In both studies, similar responses were observed in the absolute rate of albumin synthesis (mg day-1 kg-1). 4. Albumin secretion time was significantly shorter (P < 0.05) after feeding in both studies, suggesting that the acute stimulation in albumin synthesis observed after feeding may in part be mediated via a post-transcriptional mechanism. 5. The response of total liver protein synthesis to oral feeding was investigated in an animal model employing adult rats studied with a flooding amount of [2,6-3H]phenylalanine.(ABSTRACT TRUNCATED AT 250 WORDS)