Polycythbmia in the Rat on a Milk-iron-copper Diet Supplemented by Cobalt

A study of the effect of certain metals on the prevention of nutritional anemia in the rat has been reported in the preceding paper (4). Animals receiving a mixture of manganese, cobalt, nickel, and zinc with iron developed a progressive anemia and died, whereas those receiving the same mixture with iron and copper developed an abnormally high hemoglobin value at the age of 7 to 9 weeks. After the high hemoglobin levels had persisted about 18 weeks, further blood studies (cell volume, erythrocyte, leucocyte, and differential leucocyte counts) were made on the group of rats receiving the mixture of metals with iron and copper, on a group receiving only iron and copper (Group II of the preceding paper (4)), and on a group of normal stock rats of comparable age. The results, which have been given in a preliminary report (3), definitely showed a polycythemia in all of the rats receiving the mixture of metals with iron and copper, while the rats receiving only iron and copper showed values approximately the same as those of the stock rats. It was evident, therefore, that one of the metals, manganese, cobalt, nickel, or zinc, or some combination of these metals, was acting with iron and copper to produce the polycythemia. The present study was made to determine which one or combination of these metals was responsible for this marked increase in hemoglobin and in red blood cells.