Polycythemia in rats following restricted food intake

¹ Department of Medicine and Unit for Research in Ageing, Albert Einstein College of Medicine, Yeshiva University, New York City

Rats were divided into two groups such that mean weight and hemoglobin and hematocrit levels were not significantly different. One group (controls) was then fed a normal chow ad libitum. The other group was fed 6 g daily (30% of normal intake) for 2 weeks. The hemoglobin levels of rats fed the restricted diet rose 1.4–3.5 g/100 ml and hematocrit level rose 2–6%. At the end of 2 weeks total red cell mass (Cr⁵¹) was 5.5–6.0 ml in the underfed groups compared with 6.8 ml in the control group. Body weight fell proportionally more than did red cell mass, elevating the calculated red cell mass per unit body weight. Serum osmolality and K⁺ were not significantly different from control values, and there was a slightly higher serum Na⁺ and Cl^– in the restricted diet group. It is concluded that restriction of food intake produced a relative polycythemia. At the end of 2 weeks of restriction an isosmotic reduction in plasma volume was present.

Key Words: diet and red cell mass • diet and cell volume, serum • osmolality, and electrolytes • starvation • hemoglobin and hematocrit

Submitted on July 5, 1963