Cardiac and peripheral lymph lipoproteins in dogs fed cholesterol and saturated fat.

Abstract

In normal dogs fed diets containing 1% cholesterol and 30% saturated fat, cholesterol concentration increased in plasma, cardiac lymph, and peripheral lymph. The increase in cardiac lymph cholesterol always exceeded that of peripheral lymph. At plateau, LDL cholesterol increased in plasma and peripheral lymph but not in cardiac lymph; HDL2 cholesterol increased in all compartments and HDLc appeared in plasma (86.6 +/- 22.2 mg cholesterol/dl) with cholesterol feeding. In cardiac and peripheral lymph, a lipoprotein fraction with ultracentrifugal and pevikon electrophoretic characteristics of plasma HDLc (designated HDL 1.063) was isolated and contained 9.4 +/- 1.3 and 11.9 +/- 6.8 mg cholesterol/dl respectively. The lymph/plasma (L/P) ratios of lipoproteins were generally higher in cardiac lymph compared to peripheral lymph. In cholesterol-fed dogs, the L/P ratios of LDL were reduced compared to control dogs while HDL2 was unaffected, indicating selective interstitial distribution of lipoproteins. On agarose electrophoresis, lymph lipoproteins migrated faster than plasma lipoproteins, suggesting subtle changes in the structure and/or composition, findings consistent with the suggestion that lipoproteins undergo modification in the interstitial space. Thus, each interstitial space, as reflected by lymph, has a characteristic mixture of lipoproteins that can be altered by a high cholesterol diet in a manner that is unique to each particular tissue compartment.