Effect of verapamil on accumulation of free and esterified cholesterol in the thoracic aorta of cholesterol-fed rabbits

In order to investigate the effect of the calcium antagonist verapamil on atherogenesis in cholesterol-fed rabbits, 3 groups of 11 animals were fed a 2% cholesterol-enriched diet for 10 weeks. One group received verapamil in a daily dose of 16 mg/kg orally plus 2 mg/kg subcutaneously. This dosage resulted in plasma concentrations of verapamil in the same range as the usual therapeutic levels in humans. Another group received verapamil in a daily dose of 8 mg/kg orally and 0.5 mg/kg subcutaneously. The third group received placebo capsules orally and isotonic saline subcutaneously. Total cholesterol concentrations in plasma over the 10 weeks were 37 ± 4, 42 ± 4 and 45 ± 3 mM ( x ± SE ) in the high verapamil-, in the low verapamil- and in the placebo group, respectively. These values were not significantly different. The distribution of cholesterol between HDL, LDL and VLDL in plasma was similar in the 3 groups. The high verapamil group had a significantly ( P < 0.05) lower concentration of cholesterol in the thoracic aorta than the placebo group (29 ± 5 vs 43 ± 9 μmol/g wet weight). The low verapamil group and the placebo group had the same aortic cholesterol concentrations. Neither dosage of verapamil affected the permeability of the aortic endothelium to plasma lipoproteins and albumin, as measured by use of radioactive tracers at the end of the experiment.