Premium
Vitamin D 3 uptake by the isolated perfused rat liver from lipoprotein fractions is separate from cholesterol and triglyceride uptake
Author(s) -
ZIV EHUD,
BARON HANOCH,
SILVER JUSTIN
Publication year - 1985
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.1365-2362.1985.tb00151.x
Subject(s) - chylomicron , medicine , cholesterol , very low density lipoprotein , endocrinology , triglyceride , lipoprotein , vitamin , chemistry , albumin , biology
. Using the isolated perfused rat liver we examined the uptake of [ 14 C] or [ 3 H] vitamin D 3 and [ 14 C] triglyceries or [ 3 H] cholesterol by the liver of normal rats, from different lipoprotein fractions, as measured by disappearance from the perfusate. When incorporated into chylomicrons only 43% of the vitamin D 3 remained in the perfusate at 60 min (i.e. 57% uptake) as compared to 68% of the triglycerides (i.e. 32% uptake). When added on very low density lipoproteins (VLDL) at 60 min 37 ± 3% ( n = 6) of the vitamin D 3 , 38 ± 2% of the cholesterol ( n = 3) ( P NS), and 83 plusmn;4% of the triglycerides ( n = 3) remained in the perfusate ( P < 0·0005 for cholesterol: triglycerides and vitamin D 3 : triglycerides). For high density lipoprotein fraction (HDL) isolated perfused livers were studied with and without albumin present in the perfusate. Without albumin 19 ± 8% ( n = 3) of the vitamin D 3 and 43 ± 8% ( n = 3) of the cholesterol remained in the perfusate at 60 min. The results with albumin present were 40 ± 1% ( n = 5) of the vitamin D 3 and 63 ± 4% ( n = 5) of the cholesterol at 60 min ( P < 0·0005). The cholesterol:cholesterol ester ratio of the VLDL fraction was 8·8:1 and of the HDL fraction 1:1·4. There was no metabolism of vitamin D 3 during the 1 h perfusion. These results suggest that vitamin D 3 is in equilibrium with the lipoprotein surface, and the hepatic uptake of vitamin D is a surface phenomenon independent of lipoprotein metabolism.