Albumin synthetic rate: a comparison of arginine and alpha-ketoisocaproate precursor methods using stable isotope techniques.
The validity of [15N]glycine and [13C]leucine as tracers for investigating albumin fractional synthetic rate (FSR) has been explored by simultaneous infusion of both amino acids into 5 normal female subjects. Albumin FSR, calculated from the urinary [15N]urea plateau value and the incorporation of arginine into albumin was 0.2250 +/- 0.038 per cent/h (mean +/- s.d.). The infusion of leucine, using alpha-ketoisocaproate enrichment to represent the precursor pool, and with measurement of the direct incorporation of leucine into plasma albumin gave a FSR of 0.2516 +/- 0.044 per cent/h. Calculated absolute albumin synthetic rates (ASR) were 11.29 +/- 1.73 mg/kg/h and 11.13 +/- 2.24 mg/kg/h for the glycine and leucine methods respectively. It is concluded that the latter approach is valid as the two amino acids yielded such similar values. The glycine-arginine protocol used represents an improvement compared with previous methods in that the study is completed within 12 h.
Olufemi
O S
OS
University Department of Obstetrics & Gynaecology, Princess Mary Maternity Hospital, Newcastle upon Tyne, UK.
Humes
P
P
Whittaker
P G
PG
Read
M A
MA
Lind
T
T
Halliday
D
D
D000328:Adult; D001120:Arginine / Q000008:administration & dosage / Q000378:metabolism*; D001798:Blood Proteins / Q000096:biosynthesis*; D002247:Carbon Isotopes; D002985:Clinical Protocols; D005260:Female; D005998:Glycine / Q000008:administration & dosage / Q000378:metabolism; D006801:Humans; D007262:Infusions, Intravenous; D007651:Keto Acids / Q000008:administration & dosage / Q000378:metabolism*; D007930:Leucine / Q000378:metabolism*; D009587:Nitrogen Isotopes; D012709:Serum Albumin / Q000096:biosynthesis*
D001798:Blood Proteins; D002247:Carbon Isotopes; D007651:Keto Acids; D009587:Nitrogen Isotopes; D012709:Serum Albumin; C013082:alpha-ketoisocaproic acid; D001120:Arginine; D007930:Leucine; D005998:Glycine