Effects of hydrophobicity on turnover of plasma high density lipoproteins labeled with phosphatidylcholine ethers in the rat |
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Authors: | H J Pownall D Hickson-Bick J B Massey |
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Institution: | Department of Medicine, Baylor College of Medicine, Houston, TX. |
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Abstract: | Rat high density lipoproteins (HDL) were labeled with a series of phosphatidylcholines and ether analogs of phosphatidylcholine. The rates of turnover of the phosphatidylcholine ethers in the rat decreased as a function of increasing hydrophobicity and were more than five times faster than those of apolipoprotein A-I turnover and spontaneous lipid transfer. The major tissue sites for uptake were the liver, adrenals, and ovaries. The rate of turnover of a phosphatidylcholine was faster than that of the corresponding ether analog due to the action of lecithin:cholesterol acyltransferase, although this activity was slow compared to the turnover of high density lipoprotein-phosphatidylcholine. Injection of a purified human phosphatidylcholine transfer protein increased the turnover rate of a phosphatidylcholine and its ether analog. We conclude that a major route for the turnover of plasma high density lipoprotein-phosphatidylcholine in the rat is independent of spontaneous lipid transfer, hydrolysis, and HDL particle uptake, and that it involves the activity of a plasma phosphatidylcholine transfer protein. |
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