The effects of calcium, magnesium, lead, or cadmium on lipoprotein metabolism and atherosclerosis in the pigeon.

Epidemiological and clinical studies suggest that the incidence of atherosclerosis is higher in soft-water areas than in hard-water areas. In an attempt to discern the factor(s) in drinking water that may be associated with these observations, the current studies were performed to determine the effects of several elements associated with hard (i.e., calcium and magnesium) or soft (i.e., cadmium and lead) water in the induction and progression of atherosclerosis in the white carneau pigeon. The effect of these elements on lipoprotein metabolism was also assessed because it has been suggested that changes in the metabolism of lipoprotein may play a role in the etiology of atherosclerosis. Results show that the number and size of atherosclerotic plaques in the aorta were increased in pigeons given drinking water containing lead and/or cadmium. The effects of these elements were antagonized by the addition of calcium to drinking water containing lead and/or cadmium. Although lead and cadmium altered the profile of lipoproteins, this change did not appear to be related to an increase in the number and size of atherosclerotic plaques of the aorta. However, in pigeons treated with calcium alone the low-density lipoprotein (LDL) increased fourfold, and arteriosclerosis of the coronary arteries was observed. This result suggests that marked increases in the LDL protein may be related to arteriosclerosis of the coronary arteries. Based on these preliminary results, we suggest that lead, cadmium, and the LDL protein may be important factors in the induction and progression of atherosclerosis and arteriosclerosis in the pigeon.