Correlation between the activities of lipoprotein lipase and paraoxonase in type 2 diabetes mellitus.
In type 2 diabetes mellitus the decreased catabolism of triglyceride-rich lipoproteins as a consequence of mainly the decreased lipoprotein lipase activity results in hypertriglyceridaemia and other lipoprotein alterations promoting atherosclerosis. The high-density lipoprotein-associated enzyme, paraoxonase, prevents the oxidation of low-density lipoprotein, which is an antiatherogenic effect.


OBJECTIVE
to examine the relation between the activities of enzymes influencing HDL remodelling- LPL and PON- in type 2 diabetes mellitus.


METHODS
56 newly diagnosed type 2 diabetic patients and 39 healthy controls were involved in the study. The serum PON activity was measured spectrophotometrically using paraoxone as substrate. PON phenotype was determined by the dual substrate method, PON mass was measured by ELISA. The determination of lipoprotein lipase activity was performed using 3H-triolein.


RESULTS
We noticed smaller PON activity decrease in our newly diagnosed diabetic subjects compared to the previous studies which investigated the alteration of enzyme activity after a longer duration of diabetes mellitus. The lipoprotein lipase activity showed a positive correlation with PON activity (r=0.43; P<0.02). Interestingly, the PON activity of the homozygous-low activity group did not correlate with the LPL activity, while in the heterozygous and homozygous-high activity groups there was a significantly positive correlation (r=0.51; P<0.05) between PON and LPL activity.


CONCLUSIONS
Besides lipid alterations, the metabolic changes of type 2 diabetes mellitus influence the reduction of the antioxidant capacity of HDL by remodelling HDL and decreasing PON activity via modification of lipoprotein lipase activity, which might contribute to accelerated atherosclerosis.
Kalmár
T
T
1st Department of Medicine, Medical and Health Science Center, University of Debrecen, Nagyerdei krt. 98, H-4012 Debrecen, Hungary. timeakalmar@hotmail.com
Seres
I
I
Balogh
Z
Z
Káplár
M
M
Winkler
G
G
Paragh
G
G
D043303:Aryldialkylphosphatase / Q000097:blood* / Q000235:genetics; D001794:Blood Pressure; D015992:Body Mass Index; D002265:Carboxylic Ester Hydrolases / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000201:enzymology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008071:Lipoprotein Lipase / Q000097:blood* / Q000235:genetics; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D012016:Reference Values
D002265:Carboxylic Ester Hydrolases; C019734:arylesterase; D008071:Lipoprotein Lipase; D043303:Aryldialkylphosphatase