Disappearance of two major phosphatidylcholines from plasma is predominantly via LCAT and hepatic lipase

1996 ◽  
Vol 271 (6) ◽  
pp. E1073-E1082 ◽  
Author(s):  
R. D. Shamburek ◽  
L. A. Zech ◽  
P. S. Cooper ◽  
J. M. Vandenbroek ◽  
C. C. Schwartz
Keyword(s):  
Bile Acids ◽  
Hepatic Lipase ◽  
Cholesterol Acyltransferase ◽  
Rat Plasma ◽  
High Density Lipoproteins ◽  
Cholesteryl Esters ◽  
Phospholipase A1 ◽  
Lipase Hydrolysis ◽  
Lecithin Cholesterol Acyltransferase ◽  
Hydrolysis Of

Metabolism of 1-stearoyl-2-arachidonyl-phosphatidyl-choline (SAPC), a major phosphatidylcholine (PC) species in rat plasma, was compared with 1-palmitoyl-2-linoleoyl-PC (PLPC) metabolism. High-density lipoproteins containing SAPC and PLPC tracers labeled in the sn-2 fatty acid with 3H and 14C isotopes, respectively, were administered. The rats were depleted of endogenous bile acids and infused via the ileum with individual bile acids that ranged widely in hydrophobicity. The half-lives for SAPC and PLPC in plasma were 48 and 57 min, respectively. Most of the 3H activity that disappeared from plasma at 1 h was found in the liver in 1-palmitoyl-2-arachidonyl-PC, SAPC, and 1-oleoyl-2-arachidonyl-PC, indicating phospholipase A1 hydrolysis of plasma SAPC forming 2-arachidonyl-lysophosphatidylcholine, which was reacylated in the liver. Plasma PLPC also underwent phospholipase A1 hydrolysis, as reported previously. The fraction of 3H dose that accumulated in plasma cholesteryl arachidonate was two- to threefold higher than the fraction of 14C dose in cholesteryl linoleate. Multicompartmental models for SAPC and PLPC were developed that included lysophosphatidylcholines and cholesteryl esters. Bile acids did not influence plasma PC metabolism. Lecithin-cholesterol acyltransferase and phospholipase A1 (hepatic lipase) hydrolysis accounted for > or = 90% of the SAPC and PLPC that disappeared from plasma; SAPC and PLPC are comparable as substrates for hepatic lipase, but SAPC is preferred by lecithin-cholesterol acyltransferase.

Effect of Ajuga iva on enzymes involved in the metabolism of cholesterol, in rat fed a cholesterol-enriched diet

2019 ◽  
Vol 50 (2) ◽  
pp. 303-313
Author(s):  
Sherazede Bouderbala ◽  
Malika Bouchenak
Keyword(s):  
Design Methodology ◽  
Cholesterol Metabolism ◽  
Cholesterol Acyltransferase ◽  
Cholesteryl Esters ◽  
Unesterified Cholesterol ◽  
Acyltransferase Activity ◽  
Content Type ◽  
Lecithin Cholesterol Acyltransferase ◽  
Male Wistar Rats ◽  
Adaptation Phase

Purpose This study aims to investigate the effect of Ajuga iva (Ai) on enzymes involved in the metabolism of cholesterol, in rat fed a cholesterol-enriched diet. Design/methodology/approach Male Wistar rats (n = 12), weighing 120 ± 5 g were fed on 1 per cent cholesterol-enriched diet [hypercholesterolemic (HC)] for 15 days (d15). After this adaptation phase, HC rats (total cholesterol = 6.5 ± 0.6 mmol/L) were divided into two groups fed the same diet and treated (Ai-HC) or not with (HC) with Ai for d15. Findings At day 15, in Ai-HC group compared to HC, serum triacylglycerol (TG) values were 1.4-fold lower (p = 0.002), whereas unesterified cholesterol (UC) contents were 1.8-fold higher (p = 0.0001). Serum phospholipids (PL) and cholesteryl esters (CE) contents and liver TG, UC, PL and CE values were not sensitive to Ai. TC/HDL-C and LDL-HDL1-C/HDL-C ratios were, respectively, 1.8- and 4-fold lower (p = 0.006 and p = 0.04). HDL2-C and HDL3-C amounts were enhanced by 40 and 74 per cent, respectively (p = 0.003 and p = 0.0001). HDL3-UC was 1.6-fold higher (p = 0.006); whereas PL contents were 1.4-fold lower (p = 0.003). HDL3-apo and HDL2-CE contents were similar between groups. A decreased of hydroxy-methyl-glutaryl-coenzyme A reductase and cholesterol 7α-hydroxylase activities (−44 and −25 per cent; p = 0.003 and p = 0.02, respectively) were noted. Lecithin: cholesterol acyltransferase activity was 1.5-fold higher (p = 0.001). Originality/value In HC rat, Ai is able to induce hypotriglyceridemia. However, it turns out that Ai may reduce cardiovascular risk by decreasing the reports of atherogenicity and modifying the activities of enzymes involved in the cholesterol metabolism.

Investigation of Serum Lipoproteins and Apoproteins in Abetalipoproteinaemia

1974 ◽  
Vol 46 (4) ◽  
pp. 457-468
Author(s):  
G. Kostner ◽  
A. Holasek ◽  
H. G. Bohlmann ◽  
H. Thiede
Keyword(s):  
Polyacrylamide Gel Electrophoresis ◽  
Cholesterol Acyltransferase ◽  
Normal Subjects ◽  
Normal Serum ◽  
High Density ◽  
High Density Lipoproteins ◽  
Total Serum ◽  
Serum Lipoproteins ◽  
Acyltransferase Activity ◽  
Lecithin Cholesterol Acyltransferase

1. The serum lipoproteins, apoproteins and lecithin—cholesterol acyltransferase activity of three patients with abetalipoproteinaemia have been studied. 2. Concentration of lipoproteins with a density of less than 1·063 was found to be 5–6 mg/100 ml of plasma. The protein part consisted only of apoAI polypeptides. 3. Concentration of total serum high-density lipoproteins was 90–100 mg/100 ml. After total delipidization of this fraction, apoproteins were separated by column chromatography. All apoA and most of the apoC peptides could be demonstrated by immunochemical methods and polyacrylamide gel electrophoresis. 4. Quantification of individual polypeptides indicated that the proportions apoAI: apoAII: apoAIII in high-density lipoproteins were not different from those observed in normal subjects. ApoCIII1 was absent in the patients' serum. In the remaining apoC peptides differences in the distribution compared with normal subjects could be demonstrated. 5. With antibodies to lipoprotein B, acetylated lipoprotein B or apolipoprotein B no reaction could be observed with abetalipoproteinaemic serum or any density fraction tested including density 1·23 infranate. 6. Isoelectric focussing of prestained lipoproteins in complete patients' serum revealed the absence of four major lipoprotein families present in normal serum. 7. Lecithin—cholesterol acyltransferase activity of abetalipoproteinaemic serum was reduced to a value of about 50% of normal but lipoproteins of patients' serum could be utilized as a substrate only to a minor degree. The maximum activity was observed only if lipoproteins of normal serum were added to the assay system.

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