Apolipoprotein B retention in the grossly normal and atherosclerotic human aorta.

Abstract

Apoliporotein B (apoB) was measured in buffer-extracted homogenates of grossly normal and artherosclerotic human aortic intima by means of an electroimmunoassay procedure. The apoB values which were expressed as microgram per mg tissue dry weight, varied widely, ranging from 0.34 to 18.45 in normal intima and from 0.8 to 12.5 in fatty fibrous plaques. No consistent differences in apoB content were found between normal intimas from thoracic and abdominal aortic regions. There was a statistically significant positive correlation between the quantity of buffer-extractable apoB in normal regions and the plasma cholesterol and triglyceride concentration. Buffer-extractable apoB values were significantly higher in fatty fibrous plaques than in ulcerated lesions from the same vessel. However, fatty fibrous plaque apoB values were significantly lower than those from grossly normal regions from the same aorta, although the topographical distribution of apoB was more widespread in plaques than in normal regions, as shown by immunofluorescence studies. This apparent discrepancy reflected the incomplete extraction of apoB from plaques as contrasted to normal regions. The relatively loosely bound apoB, extractable by standard buffers, may represent intact low density lipoprotein (LDL) and/or very low density lipoprotein (VLDL), while the tightly bound fraction may represent insoluble complexes of intact lipoproteins within the plaque or delipidated apoB.

Sensitization of isolated canine coronary arteries to calcium ions after exposure to cholesterol.

“…This estimate of the solubility of cholesterol in aqueous solvent is in basic agreement with that obtained using a fluorescent label technique (L. C. Smith, personal communication; Kao et al, 1977;Charlton et al, 1978). Recent studies indicate that human low density lipoprotein, the lipoprotein richest in cholesterol, accumulates in arterial walls in proportion to its concentration in plasma (Hoff et al, 1977) and appears in peripheral lymph in concentrations that are approximately one-tenth that in plasma (Reichl et al, 1978). Assuming that the lipid composition of lipoproteins in interstitial fluids is not substantially different from that of plasma lipoproteins, only approximately 1 millionth the concentration of bound cholesterol would be required to saturate the aqueous phase with cholesterol.…”

Lipid composition of aorta of Watanabe heritable hyperlipemic and comparably hypercholesterolemic fat-fed rabbits. Plasma lipid composition determines aortic lipid composition of hypercholesterolemic rabbits.

“…The cholesteryl esters were hydrolyzed in 1 N alcoholic KOH for 1 hour at 80°C and were extracted again in hexane and water. An average recovery of cholesteryl ester of more than 90% was determined using an aliquot of 14 C-cholesteryl linoleate added to the minced aorta before homogenization. The cholesterol mass of both free and esterified cholesterol was determined colorimetrically for higher concentrations (the concentration range of the standards was 5 to 150 /ig) 26 and enzymatically for lower concentrations, such as those extracted from the control animals (standard range was 0.25 to 5 /xg) 27 Standards of intermediate concentration were analyzed by using both methods to ensure that the two methods were equivalent.…”

Glycosaminoglycans and apolipoproteins B and A-I in human aortas. Chemical and immunological analysis of lesion-free aortas from children and adults.

“…Buffer-soluble lipoproteins were extracted overnight at 4° C with gentle agitation in 0.13 M Tris-HCI (pH 7.4) containing 0.1% EDTA. 11 The extract was collected by centrifugation (5000 g, 4° C, 15 minutes); the pellet was washed twice with the buffer and was analyzed for residual lipids and nonlipid components (i.e., lipids and nonlipid components that remained in the tissue after the extraction of buffer-soluble lipoproteins; see below). Apo B and apo A-l in the combined supernatants were quantified in duplicate using radial immunodiffusion 23 in 1% agarose gel containing antibodies against human plasma LDL and purified human apo A-l. 24 The antibodies were produced in New Zealand white rabbits.…”