Compensatory and obligatory renal growth in rats.

SILBER, SHERMAN, AND RICHARD L. MALVIN. Compensatory and obligatory renal growth in rats. Am. J. Physiol. 226(l) : 114-l 17. 1974.-Renal size and function were studied in three groups of rats in an attempt to gain information relating to the control of renal size. One group consisted of normal rats into which a third kidney was transplanted; a second group consisted of unilaterally nephrectomized rats in which a second hypertrophied kidney was transplanted so that each rat had two hypertrophied kidneys immediately following transplant. Rats with three kidneys maintained GFR and RPF approximately 50y0 greater than control levels, and none of the three kidneys showed any reduction in size. Unilaterally nephrectomized rats showed the usual hypertrophic response. However, when a hypertrophied kidney was transplanted into rats previously unilaterally nephrectomized, both kidneys shrank back to their control size, GFR and RPF. These results are consistent with the hypothesis that compensatory hypertrophy is a growth phenomenon different from normal growth and is reversible, although normal growth is not reversible.