Erythropoietic action of dexamethasone on the anemia associated with an experimental chronic renal failure.

Partially nephrectomized anemic uremic rats were injected with dexamethasone phosphate (10, 50 and 500 micrograms/kg/day), i.p., and erythropoietin (5 U/day), s.c., for 10 days. A marked and usually significant stimulatory effect on erythropoiesis was seen in all uremic animals treated. Administration of erythropoietin and dexamethasone produced a pronounced increment in hemoglobin, hematocrit and circulating reticulocytes. The increase in red blood cell production was also evident through the generally increased absolute numbers of nucleated erythroid cell precursors per milligram of bone marrow. The highest increases were seen in the erythropoietin treated uremic rats. A dose effect correlation was apparent in uremic rats receiving 3 different doses of dexamethasone. Dexamethasone may stimulate erythropoiesis in our anemic uremic rats through a previous augmentation of erythropoietin production in the residual renal mass. A synergistic permissive effect of dexamethasone increasing the sensitivity of the erythropoietin-responsive cells to erythropoietin in bone marrow is also quite possible.

Erythropoietic action of dexamethasone on the anemia associated with an experimental chronic renal failure.

Partially nephrectomized anemic uremic rats were injected with dexamethasone phosphate (10, 50 and 500 micrograms/kg/day), i.p., and erythropoietin (5 U/day), s.c., for 10 days. A marked and usually significant stimulatory effect on erythropoiesis was seen in all uremic animals treated. Administration of erythropoietin and dexamethasone produced a pronounced increment in hemoglobin, hematocrit and circulating reticulocytes. The increase in red blood cell production was also evident through the generally increased absolute numbers of nucleated erythroid cell precursors per milligram of bone marrow. The highest increases were seen in the erythropoietin treated uremic rats. A dose effect correlation was apparent in uremic rats receiving 3 different doses of dexamethasone. Dexamethasone may stimulate erythropoiesis in our anemic uremic rats through a previous augmentation of erythropoietin production in the residual renal mass. A synergistic permissive effect of dexamethasone increasing the sensitivity of the erythropoietin-responsive cells to erythropoietin in bone marrow is also quite possible.

Erythropoietic effects of triiodothyronine on the anemia of renal failure in rats: comparative studies with testosterone and erythropoietin.

A pronounced and significant stimulatory effect on erythropoiesis was observed in anemic uremic rats receiving either T3 (50 micrograms/kg/day) or Ep (7.5 and 15 U[units]/day) for ten days. A lack of erythropoietic response was seen after the administration of testosterone (5 mg/kg/day) for the same period of time. Renal failure and anemia were studied in partially nephrectomized rats that had received nephrotoxic doses of kanamycin (500 mg/kg/day). The marked increase in red blood cell production produced by T3 and Ep in anemic uremic rats was evident, not only from increased hemoglobin and hematocrit values in peripheral blood, but also from an elevated number of circulating reticulocytes and generally increased absolute counts of nucleated erythroid cells per milligram of bone marrow. The effects of T3 on erythropoiesis in anemic rats with renal insufficiency are in accordance with our previous report demonstrating the direct effect of thyroid hormones on marrow erythroid precursors. This effect can occur only when high levels of the free active forms of T3 are present in plasma, as can happen in the uremic rats receiving daily doses of T3. Since the possibility of producing large amounts of Ep for the treatment of the anemia associated with chronic renal failure is unlikely in the near future, utilization of T3, mainly compounds without calorigenic effects, may be a potential therapeutic alternative.