Compensatory renal hypertrophy in hypophysectomized rats.

1. After hypophysectomy, both body and kidney weights fall, but at different rates. The rate at which the kidney decreases in weight is faster than that of the whole body.2. Seven days after unilateral nephrectomy, the dry weight of the remaining kidney of hypophysectomized rats, with the exception of rats which had been hypophysectomized for 2 days only, was always heavier than the kidney of control hypophysectomized rats of similar body weight.3. The difference between the dry weight of kidneys of unilaterally nephrectomized hypophysectomized and control hypophysectomized rats increased from 15% in early hypophysectomized (9 days) to about 35% in late hypophysectomized animals (23 days).4. The implantation of renal cortical cells from 2 day hypophysectomized rats into unilaterally nephrectomized control litter-mates inhibited compensatory renal hypertrophy in the latter. When a similar operation was made using kidney cells from animals which had been hypophysectomized for 23 days, there was no significant inhibition of compensatory renal hypertrophy.5. The renal contents of adenosine-3',5'-monophosphate (cyclic AMP) and of guanosine-3',5'-monophosphate (cyclic GMP) in rats hypophysectomized for 2 days were of the same order as those in normal rats, but were markedly lower in rats hypophysectomized for 23 days.6. In contrast to what had been observed in normal rats, in hypophysectomized (2 or 23 days) rats, unilateral nephrectomy did not affect significantly the levels of cyclic nucleotides in the remaining kidney.7. Cross-circulating anephric normal rats with 2 day hypophysectomized animals resulted in an increase of cyclic GMP content in their kidneys. The cross-circulation between anephric normal rats and 23 days hypophysectomized rats had no effect on the level of renal cyclic GMP of the latter.8. When rats hypophysectomized for either 2 or 23 days and which had been nephrectomized were cross-circulated with normal rats, there were no changes in the content of cyclic GMP in the kidneys of the latter.