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Summary. Erythropoiesis was suppressed in mice by hyperoxia (HOX) and/or post-hypoxic plethora (PCT), the cytocidal effects of actinomycin-D (ACT), or by a combination of these techniques. When 19-nortestosterone decanoate (19-ND) was injected during HOX and 24 hr 59Fe incorporation was measured during and following HOX, the increment in androgen-induced erythropoiesis compared to vehicle-treated controls was significantly greater in the post-HOX assay system, where erythropoietin (ESF) titres were increased as compared to the response seen in the ESF suppressed mouse maintained in HOX. When erythropoiesis was suppressed by HOX and ACT, erythropoiesis was sustained in the 19-ND-treated mouse for a longer period than in the vehicle-treated controls. In addition, when these mice were removed from HOX to ambient conditions and all injections were terminated, erythropoiesis recovered more rapidly in the groups previously treated with the androgen. When ESF was injected to PCT-HOX mice only 24 hr after they received a single 19-ND injection, it was observed that these mice had significantly greater levels of 59Fe incorporation than identical mice injected with ESF alone. In addition, it was found that HOX was capable of significantly decreasing the already minimal levels of erythropoiesis found in the plethoric mouse and that this PCT-HOX animal did not respond as markedly to androgen administration as the plethoric animal maintained at ambient conditions. It was concluded that the data presented in this report are compatible with the concept that the androgenic steroid, 19-ND, has a direct affect on the haematopoietic stem cell pool by increasing the size of a stem cell population capable of responding to ESF and that further differentiation of these elements is dependent on the availability of ESF to the target tissue.

The effect of an androgen, 19-nortestosterone decanoate (19-ND), on radioironincorporation into peripheral red blood cells wastested in the plethoric (PCT) and the plethorichyperoxic(PCT-HOX) mouse. When 19-ND wasinjected 24 hr prior to the administration of exogenouserythropoietin (ESF), it was observedthat these mice responded with significantlygreater levels of erythropoiesis, as measured by50Fe incorporation into peripheral red blood cells,as compared to identical mice injected with ESFalone. Additional observations showed that hyperoxia(HOX) was capable of significantly decreasingthe already minimal levels of erythropoiesisnormally found in PCT mice and that this PCTHOXanimal did not respond as markedly toandrogen therapy as the PCT animal. The additionof assayable minimal amount of ESF didnot cause further augmentation of radioiron incorporationin the groups receiving ESF only.Since plasma ESF activity was not found to beelevated to detectable levels following androgenadministration in PCT-HOX mice,...

The mean concentration of the soluble organic phosphate pool (2,3-DPG) of erythrocytes of female mice was greater than that of males. This pool is predominantly 2,3-DPG and, to a lesser extent ATP. Their concentration in the erythrocyte was shown to increase through the estrous cycle with the lowest concentration observed during proestrus. The concentration did not appear to be inversely related to either the concentration of hemoglobin or the mean cell hemoglobin concentration (MCHC) of the erythrocyte. During pregnancy in the mouse the concentration of the soluble organic phosphate pool in erythrocytes increased between the 9th and 19th day of gestation. In the number of mice studied, this increase did not appear to be inversely related to the MCHC, to the hemoglobin concentration, or to the number of fetuses. A striking increase of the concentration of the erythrocyte soluble organic phosphate pool occurred following injection of 10 μg of estradiol valerate per day, for 3 days, into normal female mice....