Determination of a Skin-Related Erythropoietic Substance

Summary A method is presented for the extraction of a hemin-stimulated, heat stable erythropoietically active fraction (HSP) from the skin of subcutaneously injected animals. The production of HSP is not species specific; similar substances were produced by the enderonic tissues of the cat, guinea pig, rabbit, rat, and mouse. While the production of HSP is coincident with inflammation produced by hemin injection, the production is not inflammation-dependent per se since other inflammatory substances tested do not stimulate production. The HSP compares favorably with erythropoietin Standard B (from human urine) for erythropoietic activity in the fasting “dehydrated” rat. Its activity has also been confirmed in the polycythemic rat. The dose-response curve for HSP administration shows a definite response to as little as 70 μg. The maximal response plateaus at a dose of about 1 mg.