Effect of Cobalt Sulfate on Erythrocyte Count of the Splenectomized Albino Rat. ∗

Abstract

Prior to 1929 little was known of the biological behavior of cobalt. Waltner and Waltner 1 showed that inorganic salts of cobalt when fed or injected into normal albino rats produced a remarkable polycythemia. Orten, Underhill, Mugrage and Lewis 2 obtained similar results. The literature of cobalt polycythemia has now become quite extensive.

Our experiments were undertaken to determine if polycythemia can be produced by cobalt in spleneetomized albino rats.

Orten, Underhill, Mugrage and Lewis 2 ashed the organs, finding the largest amounts of cobalt in the liver, pancreas and spleen and minute quantities in the bone marrow.

Since it is not possible to remove the liver or pancreas in recovery experiments, cobalt was tried on spleneetomized rats, in view of the long disputed question of the hematopoietic spleen function.

Fourteen healthy, adult, white rats, mostly of the Wistar strain were used, 8 being spleneetomized under sodium pentobarbital (40 mg./kg.) and morphine sulfate (10 mg./kg.) anesthesia. An incision 2.5 cm. long was made just below the left costal margin. The lieno-renal, gastrosplenic and splenic vessels were tied and the spleen removed aseptically; the animals then placed for an hour in oxygen 90%, carbon dioxide, 10%.

After 3 weeks, cobalt injections were started. Duplicate erythrocyte counts were made routinely before and after injections; at first, weekly; later, fortnightly, using Max Levy counting chambers and Yankee Certified mixing pipettes, and Hayem's diluting fluid. Two control spleneetomized rats were used. The remaining 6 operated animals and 6 unoperated animals received cobalt daily. Blood was taken from the projecting tail, the animal being confined in a closely fitting box, to avoid excitement. Animals weights were charted at each count; and at the height of the polycythemia in the normal animals, specific gravity tests on all of the rats were made by the chloroform-benzene method without significant variations from the normal.