THE PITUITARY BODY 



tract (Knowlton, Curtis, and Silverman, 1927). Precisely 

 how the effects of posterior-lobe extract or the vasopressor 

 principle are modified by anesthetics is a matter of debate. 



In 1913 von den Velden reported that the subcutaneous 

 injection of a posterior-lobe extract inhibited water diuresis 

 in man. During the antidiuretic period the urine contained 

 an increased amount of chloride, phosphate, and total nitro- 

 gen. Von den Velden's general findings have everywhere been 

 confirmed and extended in both man and other mammals. 

 This diuresis-inhibiting effect in unanesthetized mammals 

 appears to be due to the vasopressor principle and is one of 

 its most characteristic actions. ^ A large part of the effect is 

 unquestionably of renal origin. It is not yet clear what is 

 the significance of extra-renal effects (on the central nervous 

 system and on other tissues); these extra-renal effects, how- 

 ever, appear to be of secondary importance and will be dis- 

 cussed briefly later. 



The results which might be obtained from an experiment 

 in a dog are illustrated diagrammatically in Figure 55. A 

 single dose of posterior-lobe extract merely delays diuresis; 

 moreover, the delayed diuresis may be greater than that fol- 

 lov/ing the administration of water alone. If repeated injec- 

 tions of both water and posterior-lobe extract are admin- 

 istered, severe symptoms including prostration may appear 

 ("water-intoxication" — Weir, Larson, and Rowntree, 1922). 



The diuresis inhibition undoubtedly is not due to an inter- 

 ference with the absorption of water from the intestines. The 

 typical antidiuretic effect can be produced on the isolated 

 kidney (Starling and Verney, 1924). Denervation of the kid- 

 ney in situ does not prevent the effects. If the kidneys have 

 been injured by the administration of cantharides or of a 

 salt of uranium, the polyuria is not reduced by the injection 



5 If no water has been administered, the subcutaneous injection of posterior- 

 lobe extract usually causes a transient diuresis followed by a period of lessened urine 

 formation (McFarlane, 1926; and others). 



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