The susceptibility of renal arterial forks in rabbits to dietary-induced lipid deposition.

The major forks of the renal arteries from 21 rabbits fed a cholesterol-supplemented diet for periods of 1-90 d were examined electron-microscopically to compare the changes in the stem of the renal arteries with those at the first main fork. Lipid accumulated preferentially in the intimal pads or cushions at the fork. Matrix vesicles diminished in number and appeared to be transformed into enlarged membrane-bound vacuoles with electron-translucent contents. Foam cells were observed particularly beneath the endothelium. The lipid in endothelial and smooth muscle cells differed from that in the foam cells, indicating the likelihood of a different metabolic response. Interstitial lipid resembled an infiltration of the matrix with separation of the mural constituents but was not associated with the increased cellular degeneration, the progressive accumulation of matrix vesicles or the augmentation of the dystrophic basement membrane changes prominent in spontaneous atherosclerosis. In the arterial stems of 2 rabbits fed cholesterol for 62 and 90 d respectively, interstitial lipid deposition occurred without intimal proliferation.