Introduction

Serum lipase activity can be measured using a wide variety of assays that utilize different substrates. In the early nineties a new synthetic substrate, 1,2-O-dilauryl-rac-glycero-3-glutaric acid-(6-methylresorufin) ester (DGGR) was introduced and was initially believed to be specifically hydrolyzed by pancreatic lipase. Previous studies in humans and dogs have shown however, that DGGR-based assays are not specific for the measurement of pancreatic lipase. The exact sources of lipase activity measured by DGGR-based assays in dog sera remain unknown.

Objectives

To determine the impact of pancreatic lipase-related proteins 1 and 2 (PLRP1 and PLRP2) on serum lipase activity as measured by DGGR-based assays.

Methods

Serum lipase activity was measured using DGGR-based assays (Diazyme on a Sirrus analyzer and EUROLyser) in 3 different canine serum samples before and after addition of various concentrations of recombinant human PLRP1 or PLRP2.

Results

Addition of up to 500 mg/L rhPLRP1 or 5 mg/L rhPLRP2 to canine serum samples had no impact on serum lipase activity using either the Diazyme or the EUROLyser assays. However, addition of 50 or 500 mg/L rhPLRP2 led to up to 10-fold increases of serum lipase activity using either assay.

Conclusions

This study confirms that DGGR is not specifically hydrolyzed by pancreatic lipase. Furthermore, DGGR is a viable substrate for PLRP2. As PLPR2 can be synthesized by extrapancreatic sources this finding could be clinically relevant. Further studies are needed to determine the clinical impact of PLRP2 on serum lipase activity as measured by DGGR-based assays in canine patients.