ANTERIOR PITUITARY GROWTH PREPARATIONS: THE RELATIONSHIP BETWEEN NITROGEN STORAGE AND OTHER CRITERIA OF ACTIVITY1

Abstract

Growth prepns. may be considered satisfactory if, when injd. subcut. in a large single dose of 200 mg., they produce N storage of 0.5 g. per kg. in dogs maintained on a complete diet high in protein. The gain in wt. following such injns. is greater than would be expected, N stored per 100 g. of gain in wt. being about 2%. There is thus evidence for water retention in excess of requirements for new tissue. Attempts to correlate the effect of growth prepns. on N storage with assays based on the gain in wt. of plateaued rats or widening of the epiphyseal disc of hypophysectomized rats failed. Failure of correlation appeared to be due to the presence, in some growth preps., of substances causing N loss, rather than to absence of any substance acting synergistically with the growth hormone to produce N storage. Phosphate output in the urine often declines even if the prepn. or mixture of prepns. injd. causes N loss.