Decrease of lipoprotein lipase activity in skeletal muscle in man during a short-term carbohydrate-rich dietary regime. With special reference to HDL-cholesterol, apolipoprotein and insulin concentrations.
Seven men took part in a study in which the diet was changed from an ordinary mixed one to a fat-rich diet [greater than 70% energy (E)] for 3 days followed by a carbohydrate-rich diet (greater than 70% E) for 3 days. Blood was drawn and muscle biopsies [for analysis of lipoprotein-lipase (LPL) activity] were taken before the study and at the end of each diet period. Insulin, apolipoprotein (apo) B, A-I and A-II, cholesterol and triglyceride concentrations were determined in serum and the lipids also in the high density lipoproteins (HDL). Serum insulin was higher (p less than 0.01) during the carbohydrate-rich diet than during the fat-rich diet (12.0 +/- 0.9 vs. 7.5 +/- 0.5 microunits/l, mean +/- SEM), as were serum-triglycerides (2.42 +/- 0.27 vs. 0.98 +/- 0.07 mmole/1, p less than 0.001). Muscle LPL activity, on the other hand, was lower (p less than 0.01), 27.3 +/- 6.1 vs. 75.1 +/- 13.2 microunits/g. HDL-cholesterol was 1.22 +/- 0.08 during the carbohydrate-rich diet which was lower (p less than 0.01) than during the fat-rich diet, 1.45 +/- 0.11. The concentration of apo A-I and A-II did not vary significantly. It is suggested that the increased insulin concentrations during a short-term, carbohydrate-rich diet may have a down-regulating effect on muscle LPL activity. Low muscle LPL activity may account for part of the elevation of serum triglycerides. An ineffective hydrolysis of VLDL-triglycerides may contribute to the variation in HDL-cholesterol concentration seen under these circumstances.
D000293:Adolescent; D000328:Adult; D001053:Apolipoproteins / Q000097:blood*; D002784:Cholesterol / Q000097:blood*; D008076:Cholesterol, HDL; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D006801:Humans; D007328:Insulin / Q000097:blood*; D008071:Lipoprotein Lipase / Q000378:metabolism*; D008075:Lipoproteins, HDL / Q000097:blood*; D008297:Male; D009132:Muscles / Q000201:enzymology*; D005082:Physical Exertion; D013997:Time Factors; D014280:Triglycerides / Q000097:blood
D001053:Apolipoproteins; D008076:Cholesterol, HDL; D004040:Dietary Carbohydrates; D007328:Insulin; D008075:Lipoproteins, HDL; D014280:Triglycerides; D002784:Cholesterol; D008071:Lipoprotein Lipase