Maturation-dependent acquired coronary structural alterations and atherogenesis in the Dahl sodium-sensitive hypertensive rat.

BACKGROUND: The Dahl sodium-sensitive hypertensive rat exhibits atherogenic lesions after the initiation of a high-sodium/high-fat diet. This study was designed to gauge the effect of a preadolescent high-fat diet on the postadolescent rate of atherogenesis after supplementation of the diet with sodium. METHODS AND RESULTS: Fifty-three Dahl S male rats were assigned to 2 dietary groups for the postweaning to early adolescence period (3 to 12 weeks): 29 to a standard diet (low-fat/low-sodium) and 24 to a high-fat/low-sodium diet. At age 9 weeks (just after puberty), animals from the high-fat group exhibited a relatively diminished density of coronary elastic fibers. There was no evidence of either lipid or monocytic infiltration of the subendothelial space. At age 12 weeks, most or all of the remaining animals in both groups were switched to a high-sodium/high-fat diet and were sampled through the following 8 weeks for the appearance of arterial lipid. After the switch, the high-fat-conditioned animals developed more extensive atherosclerotic pathological lesions more rapidly than their prepubertal standard-diet counterparts. The importance of the animal's stage of maturation in this effect was underscored by the observation that delaying onset of the high-fat diet to early adolescence resulted in no ultimate difference from the pubertal controls in elastic fiber density. CONCLUSIONS: The maturation-dependent high-fat conditioning of these postweanling rats correlated with an accelerated rate of atherogenesis on the initiation of the high-sodium/high-fat diet, possibly as a direct result of an alteration in arterial elasticity.

Pulse-pressure-driven neutral lipid accumulation and correlative proinflammatory markers of accelerated atherogenesis.

In athero-prone areas of the human aorta, an accumulation of neutral lipids in the arterial intima precedes the arrival of monocytes and the initiation of the fatty streak. This study continues the investigation of a similar preinflammatory process in the coronary arteries of the sodium-sensitive hypertensive Dahl S rat, focusing on the hemodynamic forces associated with the neutral lipid influx and on concurrent changes in serum levels of certain proinflammatory markers. Animals were conditioned from weaning on a high-saturated fat, high-cholesterol diet until early adolescence (age 12 weeks), at which point dietary sodium was increased, and changes in blood pressure, serum analytes and histologic markers were tracked. The first half of the 12-day induction period was characterized by an immediate rise in pulse pressure that persisted above baseline. Serum levels of free monomeric C-reactive protein (mCRP) (as monomer/dimer ratio by Western blot densitometry) rose concurrently with pulse pressure and preceded the influx of neutral lipid into the arterial intima. Levels of oxidized LDL-cholesterol (oxLDL) closely tracked that of neutral lipid accumulation. In this model, elevated pulse pressure appears to drive the activation of circulating CRP and the influx of neutral lipids into the arterial intima, which leads to increased oxLDL levels.