Submitted on July 27, 2007
Revised on September 4, 2007
Accepted on September 10, 2007
Appraisal of hepatic lipase and lipoprotein lipase activities in mice
Geesje M. Dallinga-Thie, Adrie J. Zonnneveld-de Boer, Leonie C. van Vark-van der Zee, Rien van Haperen, Teus van Gent, Hans Jansen, Rini de Crom, and Arie van Tol
Vascular Medicine G1-113, AMC, Amsterdam 1100 DD
Corresponding Author: g.m.dallinga{at}amc.uva.nl
A variety of methods are currently used to analyse hepatic lipase (HL) and lipoprotein lipase (LPL) activities in mice. In search of a simple methodology we analysed mouse pre-heparin and post-heparin plasma LPL and HL activities using specific polyclonal antibodies raised in rabbit against rat HL (anti-HL) and in goat against rat LPL (anti-LPL). As an alternative, we analysed HL activity in the presence of 1 M NaCl, a condition known to inhibit LPL activity in humans. The assays were validated using plasma samples from wild type and HL-deficient C57BL/6 mice. We now show that the use of 1 M NaCL for the inhibition of plasma LPL activity in mice may generate incorrect measurements of both LPL and HL activities. Our data indicate that HL can be measured directly, without heparin injection, in pre-heparin plasma, because virtually all HL is present in an unbound form circulating in plasma. In contrast, plasma LPL is only present in post-heparin plasma. Both HL and LPL can be measured using the same assay conditions (low salt and presence of apoCII as LPL activator). Total lipase activity in post-heparin plasma minus pre-heparin HL activity reflects LPL activity. Specific antibodies are not required.
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