Paraoxonase and arylesterase activities in the serum of two hyperlipoproteinaemic patients after repeated extracorporal lipid precipitation

The effect of heparin-induced extracorporal lipid precipitation (HELP) on t he activities of paraoxonase (EC 3.1.8.1) and arylesterase (EC 3.1.1.2) was studied in serum of a patient with hyperlipoproteinaemia (A) and of a pati ent with non-insulin dependent diabetes mellitus and hyperlipoproteinaemia (B), The enzyme activities were measured spectrophotometrically (Tris-HCl b uffer, pH 7.4, 37 degrees C) with paraoxon and phenylacetate as substrates of paraoxonase and arylesterase, respectively. Both patients underwent HELP applications once a week over a period of 7 weeks. Over that period no ove rall change was observed either in enzyme activities or in the lipid and pr otein content of the sera. However, each HELP session caused an immediate d ecrease of EDTA-insensitive arylesterase activity (on average 56% in A and 42% in B), while EDTA-sensitive arylesterase remained almost unaltered. Par aoxonase remained unchanged in A, but decreased in B (similar to 60%). Of t he atherogenic lipoprotein parameters, the most pronounced decrease was fou nd in VLDL-cholesterol and in triglycerides (on average 45% in A and 32% in B), while the anti-atherogenic HDL-cholesterol decreased < 10%. Possible i mplications of the effect of HELP on the enzyme activities studied remain t o be explained. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.