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Diurnal changes in serum triglycerides as related to changes in lipolytic enzymes, (apo) lipoproteins and hormones in normal subjects on a carbohydrate‐rich diet
Author(s) -
MIRANIOOSTDIJK C. PAGANO,
HAVEKES L.,
TERPSTRA J.,
FRÖLICH M.,
GENT C. M. VAN,
JANSEN H.
Publication year - 1983
Publication title -
european journal of clinical investigation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.164
H-Index - 107
eISSN - 1365-2362
pISSN - 0014-2972
DOI - 10.1111/j.1365-2362.1983.tb00105.x
Subject(s) - endocrinology , medicine , chemistry , triglyceride , lipoprotein lipase , adipose tissue , hepatic lipase , carbohydrate , phospholipid , cholesterol , circadian rhythm , metabolism , high density lipoprotein , diurnal temperature variation , lipase , enzyme , biology , biochemistry , atmospheric sciences , membrane , geology
. Normal subjects in steady state on a carbohydrate‐rich diet (three equivalent meals a day at 9.00, 13.00 and 17.00 h), show a wave‐like serum triglyceride (TG) pattern with a peak at 14.00 h. Post‐heparin lipoprotein lipase (LPL) activity increased from a mean value of 49 mU/ml ± 13 (SD) in the fasting state to 127 mU/ml ± 18 in the fed state ( P < 0±005). This was due to an increase in adipose tissue LPL activity which, at 16.30 and 21.30 h, was significantly higher than basal levels (12.3 ± 81.5 and 87.7 ± 23.2 v. 43.3 ± 9.3 mU/g, P < 005 and P < 001, respectively). Skeletal muscle LPL activity was low (5.8 mU/g ± 2.3, mean ± SD) and showed no diurnal change. The observed changes in TG‐hydrolysing capacity in the course of the day might explain the TG‐pattern. High density lipoprotein (HDL) subfractions HDL 2 and HDL 3 were separated by density gradient ultra‐centrifugation and had mean hydrated densities of 1088 and 1135 g/ml, respectively. While HDL 2 showed no diurnal change, HDL 3 ‐cholesterol and ‐phospholipid significantly increased during the day ( P < 0.005 and P < 0.001 respectively), reaching their highest levels in the evening. Since the rise in HDL 3 ‐lipids follows the fall in serum TG, this provides further indication that the metabolism of these fractions is mutually related.