IDENTITY AND SPECIFICITY OF FROG WATER-BALANCE PRINCIPLE OF POSTERIOR PITUITARY EXTRACT

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Abstract
Rana pipiens kept in water responds to admn. of posterior pituitary extract by an increased rate of water uptake through the skin. An assay method for this water-balance effect employing wt. gain in 3 hrs. was applied to pituitrin, pitocin and pitressin. Pitocin has the same water-balance activity as pituitrin, the minimum effective dose being approx. 0.05 units/ 100 g. Pitressin has approx. 1/10 this activity. Intermedin, desoxycorticosterone acetate, desoxycorticosterone glucoside, aqueous adrenal cortical extract, estradiol. progesterone, testosterone propionate and adrenocorticotropic hormone exert no definite effect on frog water balance even in relatively high doses. The water-balance principle appears to be a specific property of the oxytocic fraction of posterior pituitary extract.