Arterial entrance and metabolism of free and esterified plasma cholesterol measured in vivo in experimental animals by a dual isotope method.
The arterial walls of 3 cholesterol-fed rabbits were exposed for 3--4 hours in vivo to homologous cholesterol-labelled plasma with a 20-fold higher [3H/14C] ratio in esterified cholesterol (EC) than in free cholesterol (FC). The [3H/14C] ratio in total cholesterol (TC) in the thoracic aorta was 0.6--0.9 times the ratio prevailing in TC in plasma. This corresponds to a transfer from plasma into the arterial wall of relatively more FC, with the low ratio, than EC with the higher ratio. The [3H/14C] ratio in FC in the arterial wall was 1.4--2.0 times the ratio in FC in plasma. This corresponds to hydrolysis of some of the entered EC, adding cholesterol with the high ratio to FC with the lower ratio. The [3H/14C] ratio in EC in the arterial wall was 0.1--1.1 times the ratio in EC in plasma. This corresponds to no esterification in the arterial wall of entered FC. The same method applied to normolipidemic cockerels gave similar results. In a kinetic model the arterial influx from plasma of FC and EC combined (lipoprotein influx) corresponded in both groups to 20--90 nl plasma per cm2 arterial surface per hour with subsequent hydrolysis of 10--50% of the entered EC. The arterial influx of FC without EC (influx by exchange) accounted for 10--25% of the total influx of cholesterol in the rabbits and 40--70% in the cockerels.
D000818:Animals; D001013:Aorta, Thoracic / Q000378:metabolism; D001158:Arteries / Q000378:metabolism*; D001692:Biological Transport; D002250:Carbon Radioisotopes; D002645:Chickens; D002784:Cholesterol / Q000097:blood / Q000378:metabolism*; D002788:Cholesterol Esters / Q000378:metabolism*; D002791:Cholesterol, Dietary / Q000378:metabolism; D005260:Female; D007553:Isotope Labeling; D011817:Rabbits; D014316:Tritium
D002250:Carbon Radioisotopes; D002788:Cholesterol Esters; D002791:Cholesterol, Dietary; D014316:Tritium; D002784:Cholesterol