Relationships in women between body mass index and the intravascular metabolism of chylomicron-like emulsions.
OBJECTIVE
To investigate whether increasing body mass index (BMI) produces increasingly intense disturbances in the metabolism of chylomicrons, the lipoproteins that carry the dietary lipids absorbed by the intestine in the circulation.


METHODS
Four groups of 10 normolipidemic nondiabetic women at the normal (BMI<25 kg/m(2)), preobese (BMI 25-30), obese (BMI 30-40) and morbid obese (BMI>40).


METHODS
Chylomicron metabolism was studied using the method of triglyceride-rich emulsions that mimic chylomicrons. The chylomicron-like emulsion doubly labeled with (3)H-triolein (TO) and (14)C-cholesteryl-oleate (CO) was intravenously injected to calculate the plasma fractional clearance rates (FCR, in min(-1)) by a compartmental analysis model. FCR-TO mirrors both the lipolysis from lipoprotein lipase that the emulsion suffers while still in the circulation, and the triglycerides portion that is not broken down and is removed from the plasma together with the remnant particles. Lipolysis index is calculated subtracting CO from TO areas under the curve.


RESULTS
FCR-TO did not differ among the four groups. The lipolysis index was positively correlated with BMI (r=0.310; P=0.05). On the other hand, FCR-CO progressively diminished from the normal to the morbid obese group (0.069+/-0.01; 0.064+/-0.01; 0.031+/-0.003; 0.029+/-0.005 min(-1), respectively, P=0.003) and there was a negative correlation between FCR-CO and BMI (r=-0.388; P=0.01).


CONCLUSIONS
In obesity, the capacity to break down chylomicron triglycerides by lipoprotein lipase in vivo increases, but the ability of the organism to remove the resulting chylomicron remnants particles progressively diminishes as the BMI rises. Remnant accumulation most likely predisposes to coronary artery disease development.
Faculty of Pharmaceutical Sciences, and Heart Institute of the Medical School Hospital (INCOR-HCFMUSP), University of São Paulo (USP), São Paulo, Brazil.
M R M
MR
Oliveira
R C
RC
Maranhão
D000328:Adult; D000704:Analysis of Variance; D001053:Apolipoproteins / Q000032:analysis; D001786:Blood Glucose / Q000032:analysis; D015992:Body Mass Index; D002250:Carbon Radioisotopes; D002914:Chylomicrons / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D007553:Isotope Labeling; D008055:Lipids / Q000097:blood; D009765:Obesity / Q000097:blood* / Q000503:physiopathology; D012372:ROC Curve
D001053:Apolipoproteins; D001786:Blood Glucose; D002250:Carbon Radioisotopes; D002914:Chylomicrons; D008055:Lipids