Measurement of branched-chain ketoacids in plasma by high-performance liquid chromatography.
Branched-chain ketoacids were isolated from plasma or serum samples by acidification, passage through a cationic exchange resin, ether extraction, and extraction of the ether layer with phosphate buffer. The recovery of 2-[1-14C]ketoisocaproate taken through these procedures averaged 95 +/- 3%. Branched-chain ketoacids were measured by high-performance liquid chromatography using a single mobile phase (sodium phosphate:acetonitrile). In normal human subjects, mean +/- SD fasting levels of 2-ketoisocaproate, 2-keto-3-methylvalerate, and 2-ketoisovalerate were 29 +/- 8, 18 +/- 4, and 12 +/- 3 microM, respectively. In normal rats, slightly different results were found: 24 +/- 10, 19 +/- 7 and 17 +/- 6 microM, respectively. In both species, levels of each ketoacid expressed as fractions of total branched-chain ketoacids were much less variable.
Walser
M
M
Department of Pharmacology and Molecular Science, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Swain
L M
LM
Alexander
V
V
D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005260:Female; D045782:Hemiterpenes; D006801:Humans; D007651:Keto Acids / Q000097:blood*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values
D045782:Hemiterpenes; D007651:Keto Acids; C016211:alpha-keto-beta-methylvaleric acid; C001505:alpha-ketoisovalerate; C013082:alpha-ketoisocaproic acid