Effect of Cortin on High Blood Non-Protein Nitrogen of Partially Nephrectomized Rabbits. ∗

Abstract

By limitation of the kidney tissue to a minimum compatible with life, blood non-protein nitrogen levels considerably higher than normal can be maintained for periods of several weeks or even months. The purpose of this paper is to report the effect of cortin, made by the method of Swingle and Pfiffner, on the blood non-protein nitrogen of partial renal insufficiency. Adult rabbits of both sexes were used in these experiments. The diet consisted of alfalfa hay plus vegetable greens twice weekly. The rabbits were fasted 12 to 16 hours before the beginning of an experiment. The cortin was administered intraperitoneally and the blood samples withdrawn from the marginal ear vein. The technique for partial nephrectomy described by Bradford 1 was used. A wedge shaped piece of kidney tissue was first removed from one kidney and after recovery from this operation the other kidney was entirely removed. The percentage of kidney tissue removed was calculated upon the basis that the total kidney tissue was twice that of the kidney removed at the second operation.

In a series of 22 rabbits it was found that when the kidney tissue was limited to 30%, the initial increase in the non-protein nitrogen of the blood was followed by several weeks of lower values, still higher than normal, and finally by increases up to 400 mg. per 100 cc. before death. These results confirm those of Anderson. 2

In Table I are given the blood non-protein nitrogen levels before and after the cortin injections. Rabbit No. 775, from which 72% of kidney had been removed, was allowed to become pregnant and 2 weeks before parturition, the non-protein nitrogen began a steady climb. This was twice interrupted and appreciably lowered by injection of cortin. Before parturition the NPN rose to 95 to 100 mg. per 100 cc. blood, which after delivery of a normal litter of 5, dropped back to 75, where it remained until an injection of 15 cc. of “cortin” preparation lowered it temporarily to 50. Four of the litter of 5 survived and remained healthy.