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Lipoprotein lipase mass and activity in plasma and their increase after heparin are separate parameters with
P Tornvall1, G Olivecrona, F Karpe
1King Gustaf V Research Institute, Karolinska Institute, Stockholm, Sweden.
Insights
Lipoprotein lipase (LPL) mass, not activity, in preheparin plasma correlated with HDL cholesterol in young myocardial infarction patients. Heparin administration releases mainly active LPL, but LPL parameters showed varied correlations with lipoproteins.
Area of Science:
- Cardiovascular Research
- Lipid Metabolism
- Biochemistry
Background:
- Lipoprotein lipase (LPL) is crucial for triglyceride hydrolysis.
- Understanding LPL's role in early-onset myocardial infarction (MI) is important.
- LPL exists in both active and inactive forms in circulation.
Purpose of the Study:
- To investigate the relationship between LPL mass and activity in plasma.
- To examine correlations between LPL parameters and plasma lipoproteins in young MI patients and controls.
- To determine if heparin administration releases active or inactive LPL.
Main Methods:
- Measured LPL mass and activity in preheparin and postheparin plasma.
- Calculated LPL parameters including postheparin increase and specific activity.
- Correlated LPL parameters with plasma lipoprotein lipid concentrations in 61 young MI patients and 69 controls.
Main Results:
- Preheparin plasma showed significantly more LPL protein than activity, indicating inactive LPL.
- Postheparin LPL mass and activity were highly correlated, with mean specific activity suggesting active LPL release.
- Preheparin LPL mass positively correlated with HDL cholesterol in MI patients, while activity showed different correlations in controls.
Conclusions:
- Heparin administration primarily releases catalytically active LPL.
- Preheparin LPL mass is a stronger predictor of HDL cholesterol than LPL activity in young MI patients.
- LPL mass and activity exhibit distinct relationships with lipoproteins, suggesting differential roles in cardiovascular disease.
Abstract:
Lipoprotein lipase (LPL) activity and mass in plasma and their increase after heparin administration were measured in 61 men who had suffered myocardial infarction before the age of 45 years and in 69 population-based age- and sex-matched control subjects without coronary heart disease to study the relations between these parameters in plasma and their correlations with plasma lipoproteins in subjects with a wide range of lipoprotein and LPL levels. There was a relatively large amount of LPL protein compared with LPL activity in preheparin plasma, indicating that the majority of circulating LPL is catalytically inactive. LPL mass and activity in postheparin plasma (postheparin minus preheparin values) were highly correlated, and the calculated mean specific activity (0.35 mU/ng) was in the range expected for catalytically active LPL. Hence, heparin releases mainly active LPL. The four LPL parameters (mass and activity in plasma and their increase after heparin administration) were not related to each other, except for postheparin plasma LPL mass and activity, and they showed different correlations with plasma lipoprotein lipid concentrations. There was a strong positive correlation between LPL mass in preheparin plasma and the HDL cholesterol level as well as weak negative relations to VLDL triglyceride and cholesterol concentrations in the patients. In contrast, preheparin LPL activity showed no correlation with the HDL cholesterol level but weak positive relations to VLDL triglyceride and cholesterol concentrations in the control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)