VASCULAR EFFECTS OF DIET-INDUCED HYPERCALCEMIA AFTER BALLOON ARTERY INJURY IN GIANT FLEMISH RABBITS

To determine whether metastatic calcification during neointima formati on can result in neointimal calcification that simulates advanced huma n atherosclerosis, 32 giant Flemish rabbits (weight 5.5 +/- 0.6 kg) un derwent overstretch balloon injury of bilateral iliac arteries and rec eived diet therapy for 8 weeks: high cholesterol (2%) and low calcium- vitamin D-2 regimen (250 mg of calcium carbonate orally 5 times weekly and 50,000 U of calciferol intramuscularly 3 times weekly; group 1; n = 5); low cholesterol (0.5%) and high calcium-vitamin D-2 regimen (50 0 mg of calcium carbonate orally 5 times weekly and 100,000 U of calci ferol intramuscularly three times weekly; group 2; n = 19); or 0% chol esterol and high calcium-vitamin D-2 regimen (group 3; n = 8). The inc idence of vascular calcification was highest (71.4%) in group 2. Eight y-one percent of calcification was medial. Residual strain measurement s of 7 thoracic aortas from group 2 compared to normal thoracic aortas from 8 control rabbits showed that residual strain was significantly increased in the calcified atherosclerotic aortas (12.3% vs 5.2%; p = 0.001). We conclude that diet-induced hypercalcemia predominantly affe cts the media despite the presence of concomitant neointima formation from balloon artery injury with or without hypercholesterolemia and in creases the residual strain more than twofold compared to normal thora cic aortas.