THE DEVELOPMENT OF PHYSIOLOGICAL 

 REGULATION OF WATER CONTENT 



E. F. Adolph 



Department of Physiology, School of Medicine and Dentistry, 

 University of Rochester, New York 



The plan of this study is to single out one way of measuring 

 the physiological regulation of body water content. This way 

 will concern water exchanges, that is, water intakes and 

 outputs. By use of it, the ontogeny of regulatory responses to 



Fig. 1. Rat in restraint frame. Drinking water is available in 



removable beaker; urine is shed into funnel. From Adolph, 



Barker and Hoy (1954). 



excesses and to deficits of water will be traced. We and others 

 found that at birth the responses whereby constancy of body 

 water is maintained are small compared to those of older 

 animals. The several relations involved in this regulation will 

 be described largely by means of data on laboratory rats. 



Water exchanges vary chiefly in the excretion through the 

 urinary tract and in the drinking into the alimentary tract. 

 They are measured upon a rat confined to a frame (Fig. 1). 

 The urinary bladder is reflexly emptied when the rat and 

 frame are raised and lowered, whereupon the urine enters the 



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