Post-heparin plasma hepatic triglyceride lipase and monoglyceride hydrolase activities in hyperlipemia induced by a sucrose rich diet.

We have previously reported that normal Wistar rats fed an isocaloric, sucrose-rich (63%) diet (SRD) developed glucose intolerance and elevated triglyceride levels in plasma as well as in heart and liver tissue. This metabolic state was accompanied by hyperinsulinism both in vivo and in vitro, suggesting that a state of insulin resistance has developed. The aim of this study was to gather information on the various plasma post-heparin lipolytic activities in rats fed a SRD. Hepatic triglyceride lipase (H-TGL) was evaluated by both, protamine sulfate inhibition (PSI) of extrahepatic lipoprotein lipase (LPL) and heparin-Sepharose affinity chromatography (H-SAC). Both methods rendered comparable results. Total triglyceride lipase (T-TGL) was measured after Krauss et al. and monoglyceride hydrolase (MGH) after Vogel et al. Our results have shown a significant decline of plasma T-TGL (5.32 +/- 0.34 means +/- SEM vs. 7.48 +/- 0.64 mumol glycerol ml-1 h-1; p less than 0.01), H-TGL (3.71 +/- 0.28 vs. 5.05 +/- 0.69; p less than 0.05), LPL (1.61 +/- 0.26 vs. 2.42 +/- 0.41; p less than 0.05) and MGH (558 +/- 108 mumol glycerol l-1 min-1 vs. 1,165 +/- 45; p less than 0.001) activities. Thus, feeding a sucrose-rich diet induced a state of hyperlipemia and insulin resistance in which not only plasma T-TGL but also H-TGL and MGH activities were significantly decreased. This suggests that the latter two enzymes are also under nutritional and/or hormonal control.