Sensitive non-radioisotopic method for measuring lipoprotein lipase and hepatic triglyceride lipase in post-heparin plasma.

In this method for measuring lipoprotein lipase (LPL) and hepatic triglyceride lipase (H-TGL) in post-heparin plasma, we determine the released free fatty acids enzymically. After release, they are extracted by Dole 's method (J. Biol. Chem. 235: 2595-2599, 1960), solubilized with Triton X-100, then measured with an enzymic kit (NEFA Kit-K; Nippon Shoji Kaisha Ltd.) after residual turbidity is removed by centrifugation with chloroform. A 5-microL sample of post-heparin plasma suffices to measure the activity of LPL and H-TGL; thus the method is as sensitive as the radioisotopic method. Selective assay of LPL and H-TGL, by adding sodium dodecyl sulfate to inactivate H-TGL or NaCl to inactivate LPL, is also feasible. The mean activities +/- SD of LPL and H-TGL in plasma of normal healthy men were respectively 9.4 +/- 2.3 mumol/h per milliliter (157 +/- 38 U/L) and 20.1 +/- 10.4 (335 +/- 173 U) mumol/h per milliliter (U/L).