The Selective Inactivation of an ESF-Generating Factor (EGF) in the Presence of Erythropoietin (ESF)

Activity of Inhibitors on Plasmatic Erythropoietin and on the Renal and Splenic Erythropoietic Factors in the Rabbit

“…It is therefore probable that it is to be identified with that described by Lewis et al [5,6] in the urine of anaemic patients: a hypothesis also sug gested by the results of other recent studies [2], The fact that in the same experimental conditions the DTT also inactivates the factor present in the spleen of the rabbit appears to be in agreement with the results of pre vious works, which show that there occurs, in the spleen, an accumulation of an erythropoietic factor produced and released into the circulation by the kidney [7,8].…”

“…The active materi al corresponding to the kidneys of a donor and prepared by the methods described above was incubated for 30 min with 5 mg of DTT at 37 °C [6]. Preliminary experi ments carried out by using scalar doses of this reagent had shown that a dose of 5 mg was sufficient to inactivate the erythropoietic factor contained in the kidneys of a normal animal.…”

“…Similar inactivation tests were then carried out by incubating DTT, known for its inability to inhibit erythropoietin [6,11], with active fractions prepared from kid ney-plasma and spleen-plasma mixtures, also making use of fractions containing er ythropoietin, since they were obtained from anaemic plasma. Also in these experi ments, high doses of the reagent were used (20-30 mg of DTT), being proportional ly equal to 10 times those sufficient to inhibit renal or splenic active fractions hav ing the same weight, since preliminary tests, carried out by using such doses (2-3 mg of DTT) had given negative results.…”

“…Lewis et al [6] later studied the effects of Cleland's reagent (2,3-dihydroxy-l-4-dithiolbutane or dithiothreitol; DTT), known for its capac ity to hinder the oxidation of the -SH groups, on the two different ery thro-stimulant factors in urine. They showed that DTT was capable of completely inactivating the erythropoietic factor content in urine, whereas it had no effect on the erythropoietin, even in very high doses.…”

“…The object of the present studies was to verify whether DTT, known for its capacity to inhibit the erythropoietinogenic factor present in the ur ine of anaemic patients [6], was equally capable of inactivating the renal erythropoietic factor and the erythropoietic factor present in the spleen of the rabbit, which it also considered to be of renal origin [8]. Another ob ject of the studies was to verify whether Koshland's reagent, known for its capacity to inhibit erythropoietin, was equally capable of inhibiting the activity of the plasma-kidney and plasma-spleen incubation products, which probably contain erythropoietin [9].…”