[Compensatory renal hypertrophy. II. - Search for a serum stimulant factor (author's transl)].

: In order to demonstrate in the uninephrectomised rat possible circulating serum factors which might induce an increase in the rate of synthesis of DNA in the remaining kidney, we injected intravenously to 125 g rats serum from similar rats uninephrectomised 24 to 48 hours previously. The injections preceded the administration of tritiated thymidine by 13 hours (1.5 ml), 5 hours (1 ml), or 2 hours (1 ml) depending on each group. The parameter studied was the radioactivity of the acid-insoluble fraction of 100 mg of kidney. We observed in uninephrectomised animals receiving no injection of serum that the rate of uptake of the tracer in the remaining kidney doubles 48 hours after nephrectomy but this uptake by the kidneys of unoperated rats is not modified by the injection of serum from similar rats whether uninephrectomised or not. Furthermore the addition of serum from uninephrectomised rats to slices of normal kidney under incubation does not modify the rate of synthesis of DNA. All these results are not in favour of a serum factor regulating compensatory renal hypertrophy.