Protective effects of dietary calcium and magnesium on platelet function and atherosclerosis in rabbits fed saturated...

Male rabbits were fed for 6 months a purified diet rich in fat (45% of calories), mostly saturated (butter) containing per 100 g either 354 mg of calcium and 46 mg of magnesium (group I), 948 mg of calcium and 46 mg of magnesium (group II), or 354 mg of calcium and 356 mg of magnesium (group III). In group II, fed the additional calcium, significant (P less than 0.001) changes were observed; i.e. prolongation of clotting time (platelet clotting activity), decrease in platelet aggregation to thrombin, and in the concentration of the plasma total cholesterol, with a less significant (P less than 0.05) decrease in plasma triglycerides. A significant (P less than 0.01) decrease in the ratio monoemes/18:2 in the plasma cholesterol esters but not in the plasma or platelet phospholipids was also found in these rabbits. In relation to their lower activity, platelets from group II exhibited a significant increase in 22:4n-6 (phospholipids) and in the ratio cholesterol/phospholipids, both significantly correlated with the platelet function tests. In this same group, the excretion of fecal lipids and saturated fatty acid 18:0 was increased by 4.3-fold and 7.6-fold, respectively. The severity of atherosclerosis and the accumulation of cholesterol in the aorta were significantly lower in group II, while the plasma level of calcium was similar to that of group I. In group III, fed additional magnesium, results were similar to those of group II, but less significant.