Assay of "Hemopoietine'"in Starved Animals; Properties of Urinary Hemopoietine

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Abstract
Intravenous injection of extracts (10 mlAg) of boiled plasma, obtained from phenylhydrazine treated rabbits, produces a clear.cut increase of plasma iron turnover (50 /[mu]g/ hr [forward arrow] 97 [mu]g/hr and of incorporation of Fe59 in erythrocytes (15[forward arrow]50% at 24 hours) of rabbits fasted for 4 days. Similar doses of these extracts increase 24-hour; erythrocyte Fe59 (10%[forward arrow]40%) and a lower, 24-hour liver Fe59 (16%[forward arrow]4%) in rats fasted 4 days. The per cent Fe59 in erythrocytes is proportional to log dose while the erythrocytes Fe59 ratio is proportional to dose of extract given. This bioassay is used to test fractions obtained by treatment with alcohol of both water extracts of boiled plasma and urine of phenylhydrazine treated rabbits. The precipitate obtained with 80% alcohol at pH 4.5 from either urine or boiled plasma, is very active. On refractionating this extract, the major part of the activity precipitates between 50-80% alcohol at pH 4.5. The active material gives a positive biuret reaction and has a neutral carbohydrate content (orcinol) greater than 10 mg/100 mg protein, thus characterizing it as a mucoprotein.