title: Catecholamine interference with enzymatic determination of nonesterified fatty acids in two commercially available test kits.
abstract: We present evidence that catecholamines, which are commonly used to stimulate lipolysis in adipose tissue in vitro, interfere with the enzymatic determination of non-esterified fatty acid (NEFA) in two commercially available kits. Measurement of a 100 mumol/L standard with the Wako "NEFA C" test kit was 60% inhibited by 100 mumol/L norepinephrine and was completely inhibited by 100 mumol/L isoproterenol or by 1 mmol/L norepinephrine or epinephrine. Measurement with the Boehringer Mannheim "Free Fatty acids, Half-micro test" was completely inhibited by 100 mumol/L norepinephrine and was also affected by concentrations as low as 0.1 mumol/L. We propose that this effect is due to the catecholamines interfering with a step common to the two kits, the generation of hydrogen peroxide and oxidation of a chromagen; furthermore, this interference appears to be stoichiometric. We also give details of an alternative in-house method, which does not depend on the generation of hydrogen peroxide and is not affected by catecholamines.
authors.affiliation: Oxford Lipid Metabolism Group, Sheikh Rashid Laboratory, Radcliffe Infirmary, UK.
authors.forename: R E
authors.initials: RE
authors.lastname: Carr
authors.forename: S M
authors.initials: SM
authors.lastname: Humphreys
authors.forename: K N
authors.initials: KN
authors.lastname: Frayn
mesh_terms: D042962:Acyl-CoA Oxidase; D002395:Catecholamines / Q000097:blood*; D003066:Coenzyme A Ligases / Q000378:metabolism; D004837:Epinephrine / Q000494:pharmacology; D005230:Fatty Acids, Nonesterified / Q000097:blood*; D006801:Humans; D006861:Hydrogen Peroxide; D007545:Isoproterenol / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D010088:Oxidoreductases / Q000378:metabolism; D011786:Quality Control; D011933:Reagent Kits, Diagnostic / Q000706:statistics & numerical data*; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D012680:Sensitivity and Specificity; D013053:Spectrophotometry; D000098859:Long-Chain-Fatty-Acid-CoA Ligase
chemical_list: D002395:Catecholamines; D005230:Fatty Acids, Nonesterified; D011933:Reagent Kits, Diagnostic; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D006861:Hydrogen Peroxide; D010088:Oxidoreductases; D042962:Acyl-CoA Oxidase; D003066:Coenzyme A Ligases; C090799:FAA2 protein, S cerevisiae; D000098859:Long-Chain-Fatty-Acid-CoA Ligase; D007545:Isoproterenol; D009638:Norepinephrine; D004837:Epinephrine