Abstract
The inhibitory effect of 15-hydroperoxy arachidonic acid (15-HPAA) on post-heparin lipolytic activity (PHLA) was studied. The procedures of PHLA was fundamentally that described by Boberg and Carlson. Human 3H-chylomicron was used as the substrate. 15-HPAA was added to the medium with a value of lipid peroxide up to 10 nmoles/ml (Yagi's method). As control, same moles of arachidonic acid was used. In saturated reaction ([S]>>Km), maximal hydrolysis rate was determined and in unsaturated reaction ([S]<<Km) half life time was measured. Km was obtained by Lineweaver-Burk plots. The obtained Km was 0.7mM in this experiments. Addition of 15-HPAA to the medium induced a decrease in approximately 20% of maximal hydrolysis rate (0.09) μmoles/ml/min to 0.072μmoles/ml/min in average), but did not change the half life time.
In conclusion, the data suggest that 15-HPAA damage at least a part of the solubilized lipoprotein lipase.
