Polycythemia and Right Ventricular Hypertrophy

Polycythemia was induced in rats by injecting 10 mg CoCl 2 /kg body wt/day intraperitoneally or by placing them in a low pressure chamber at a reduced barometric pressure equivalent to 18,000 feet of altitude for approximately 23 hours/day. After 63 days of treatment a significant hypertrophy of the right ventricular wall was found in both groups of animals. The increase in weight of the right ventricle in the CoCl 2 -injected rats was approximately 45% of that found in rats exposed to chronic hypoxia. Polycythemia was induced in mice by injecting 0.5 ml of packed, whole erythrocytes per day, intraperitoneally, for four consecutive days. A high hematocrit was maintained by additional periodic intraperitoneal injections of erythrocytes. After twenty-two days a significant right ventricular hypertrophy was observed. It is concluded that polycythemia and hypervolemia are important factors in producing right ventricular hypertrophy in rats and mice without airway hypoxia and also may be significant factors in the cardiac hypertrophy induced by high altitude.