The conception has been advanced that the kidney, under normal conditions and with respect to tubular activity in the reabsorption of water, is subject to stimulation by the antidiuretic hormone, the degree of stimulation being proportional to the amount of hormone present in the blood and, consequently, to the rate of pituitary secretion. Furthermore, the secretion of the pituitary may be governed in turn by nervous stimuli or by changes in the composition of the blood transmitted to the gland through mediation of the central nervous system. This theory of a control of urine volume by the pituitary is attractive and has been called on to explain variations in water excretion which occur under diverse circumstances, including water diuresis.
Reports conflict with regard to proof of the presence of antidiuretic hormone in body fluids in concentrations which vary with physiologic variations in urine volume.
As pointed out by Walker,1