The Effect of Hypophysectomy on Compensatory Renal Hypertrophy in Dogs *

It is well known that such mechanical factors as arterial hypertension or valvular defects increase the work of the myocardium and so result in cardiac enlargement. The amount of this compensatory response, however, varies strikingly from case to case. Even when all the known factors tending to produce hypertrophy and those known to limit it are comparable, some hearts are found at autopsy to have doubled their size while others have remained essentially unchanged. These differences are at present unexplained and stimulate further interest in the actual mechanism of the compensatory process itself. Compensatory hypertrophy is easily produced in one kidney after ablation of the other. This has been shown to occur in dogs, rabbits, and rats1'2,9, 1 Furthermore, McQueen-Williams and Thompson,' in carefully controlled experiments on rats, have shown that hypertrophy does not occur if the pituitary has been removed. Failure of the remaining kidney to enlarge after hypopliysectomy has been reported by Gonzalez! in experiments on batrachians. Similar results with rat adrenal and thyroid have been obtained.4'5 11 It is the purpose of this paper to contribute a preliminary report on the relation of the pituitary body to compensatory renal hypertrophy in dogs.