A novel method for measuring human hepatic lipase activity in postheparin plasma
Journal of Lipid Research
The objective of this study was to establish a hepatic lipase (HL) assay method that can be applied to automatic clinical analyzers. Seventy-four hyperlipidemic subjects (men/women 45/29) were recruited. Lipase activity was assayed measuring the increase in absorbance at 546 nm due to quinonediimine dye production. Reaction mixture R-1 contained 50 mM Tris-HCl (pH 9.5), 0.5 mM glycerol-1,2dioleate, 0.4% (unless otherwise noted) polyoxyethylenenonylphenylether, 3 mM ATP, 3 mM MgCl 2 , 1.5 mM
... MgCl 2 , 1.5 mM CaCl 2 , monoacylglycerol-specific lipase, glycerol kinase, glycerol-3-phosphate oxidase, 0.075% N,N-bis-(4-sulfobutyl)-3methylaniline-2 Na, peroxidase, ascorbic acid oxidase. Reaction mixture R-2 contained 50 mM Tris-HCl (pH9.5), 0.15% 4-aminoantypirine. Automated assay for activity was performed with a Model 7080 Hitachi analyzer. In the lipase assay, 160 ml of R-1 was incubated at 37jC with 3 ml of samples for 5 min, and 80 ml of R-2 was added. Within-run coefficient of variations was 0.9-1.0%. Calibration curve of lipase activity was linear (r 5 0.999) between 0 and 320 U/l. Analytical recoveries of purified HL added to plasma were 96.6-99.8%. HL activity in postheparin plasma measured in this method had a closer correlation with HL mass by a sandwich ELISA (r 5 0.888, P , 0.0001) than those in the conventional method using [ 14 C-]triolein (r 5 0.730, P , 0.0001). This assay method for HL activity can be applied to an automatic clinical analyzer.-Imamura, S., J. Kobayashi, S. Sakasegawa, A. Nohara, K. Nakajima, M. Kawashiri, A. Inazu, M. Yamagishi, J. Koizumi, and H. Mabuchi. A novel method for measuring human hepatic lipase activity in postheparin plasma. J. Lipid Res. 2007. 48: 453-457.