Effect of dietary fat saturation on plasma lipoproteins and high density lipoprotein metabolism of the rhesus monkey.

Abstract

Rhesus monkeys were fed corn or coconut oil-based diets for 3-6 mo to determine effects on the composition of all lipoprotein classes and on the metabolism of high density lipoproteins (HDL). Major findings included the following. (a) Coconut oil feeding increased concentrations of all classes of plasma lipoproteins without altering lipoprotein size, suggesting an increase in particle number. (b) The percentage of saturated fatty acids in the cholesteryl esters (CE) of low density lipoproteins (LDL) and HDL reached 40% with coconut oil feeding. This value probably constitutes a minimum estimate of the CE which were of intracellular rather than intraplasmic origin. (c) The CE in LDL and HDL were nearly identical suggesting virtually complete equilibration by the core lipid transfer reaction. The CE in very low density lipoproteins, in contrast, were significantly more saturated than those in LDL and HDL irrespective of diet. (d) Lower HDL levels on the corn oil diet were associated with higher fractional catabolic rates for both apolipoprotein A-I (OA2 vs. 031 d-l) and apolipoprotein A-Il (OA5 vs. 0.30 d-').

Effect of dietary fat saturation and cholesterol on LDL composition and metabolism. In vivo studies of receptor and nonreceptor-mediated catabolism of LDL in cebus monkeys.

“…16 Apo A-l and apo B were measured by radial immunodiffusion (RID) using antj-cebus apo A-l and LDL as we have previously described. 10 Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed according to the method of Weber and Osborne. 17 Liver and adipose tissue samples were obtained by biopsy in anes-thetized animals, and lipoprotein and tissue lipids were extracted by the method of Folch et al 18 Total and free cholesterol were measured by gas-liquid chromatography as described by Bates et al 19 Cholesterol ester was determined after the subtraction of free cholesterol from total cholesterol and was multiplied by 1.68 to correct for fatty acid content.…”

“…Fatty acid analyses of the two dietary fats have been reported elsewhere 10 ; coconut oil, rather than butter or animal fat, was used because it does not contain any cholesterol, and its ingestion is associated …”

“…10 Briefly, monkeys were acclimated to metabolic restraining chairs before the study. This was accomplished over several weeks by introducing each monkey to the chair for short periods (less than 1 hour) and eventually up to 8 hours, the longest duration of chair-restraint to which each monkey was subjected.…”

“…The plasma disappearance curve of native or glucosylated LDL apo B ( Figure 1) was analyzed by using the general principles defined by Matthews. 26 The slopes (b, and b j and the intercepts (c, and c^ were calculated (as we have reported previously 10 ) by computer methods with a curve-peeling program that uses least-squares analyses.…”

“…The triglyceride fatty adds generally reflected the diet composition with some notable exceptions. For example, although coconut oil contains approximately 49% lauric acid (12:0), 10 See the legends for Tables 3 and 4 for an explanation of abbreviations.…”