Mechanism of the decreased erythropoiesis in the water deprived rat

Radioiron uptake by erythrocytes, metabolic rate, erythropoietin formation during hypoxia and erythroid responsiveness to exogenous erythropoietin were determined in both starved and water deprived rats. The feed intake showed a marked and progressive reduction during water deprivation. The metabolic rates of rats deprived of either food of water declined progressively showing a 40% reduction 5d after water deprivation or starvation began. At this time, the 24 h red blood cells 59Fe incorporation was 85% lower in both starved and dehydrated rats than in normal rats. Plasma erythropoietin levels in response to hypoxia were approximately 50% decreased in both starved and dehydrated rats. Both polycythaemic starved and polycythaemic water deprived rats injected with human urinary erythropoietin showed a 75% decrease in 59Fe incorporation into erythrocytes when compared to control rats. It is suggested that depression of erythropoiesis during water deprivation in the rat depends on a reduced sensitivity to erythropoietin, possibly associated with decreased production of the hormone. Since water deprived rats drastically reduce feed intake it is suggested that secondary starvation is the principal cause of the decreased erythropoiesis induced in the rat by water deprivation.