The Physiological Basis of Urinary Bladder Hypertrophy 1

Summary When both kidneys are removed from one partner of parabiosed rats, the unused bladder atrophies while that of the intact partner hypertrophies. This hypertrophy is brought about by a prompt and sustained increase of 30% in the frequency of micturition, together with a more gradual rise in the quantity of urine excreted at each voiding. The capacity of such bladders levels off at approximately double preoperative values by the fifth week, while the heightened frequency of urinations remains elevated. The two remaining kidneys of the intact rat undergo hypertrophy in compensation for the renal losses of its partner, but the degree of enlargement is less than half that observed in single rats deprived of one kidney.