EXTRACTS OF THE PARS NEURALTS 



and others (1937) demonstrated this phenomenon by observ- 

 ing the diuresis-inhibiting action of posterior-lobe extract 

 with and without the addition of acetates of Zn, Ni, or Cd to 

 the extract. 



Jones and Schlapp (1936) found that both principles are 

 metabolized alike after their intravenous injection in a large 

 dose (about 20 units per kilogram body-weight) into decapi- 

 tated cats. Within 20 minutes most of the hormones (85 

 per cent) had disappeared from the blood; there was none 

 present after 2 hours. About 30 per cent of the extract in 

 terms of vasopressor hormone could be recovered from the 

 urine. The work of Heller (1937) indicated that, after the 

 intravenous injection of posterior-lobe extract into the rabbit 

 (and rat), the vasopressor hormone, measured by its diuresis- 

 inhibiting effect, is excreted in the urine up to about 30 

 minutes after injection. Apparently, the amount excreted is 

 not proportional to the dose but is limited because of un- 

 known factors. Consequently, the higher the injected dose, 

 the lower is the proportion of hormone recovered in the 

 urine. Heller has found that blood adsorbs the hormone and 

 has concluded that the kidney liberates the adsorbed hor- 

 mone which is excreted at its point of action, the renal 

 tubules.'^ 



Certain tissues, especially the liver, can rapidly adsorb 

 vasopressor hormone. According to Heller and Urban (1935), 

 the adsorbing substance is heat labile and can be removed by 

 animal charcoal. The hormone can be released from the ad- 

 sorbent by boiling in saline solution. In addition, blood or 

 liver contains an enzyme-like substance which destroys the 

 hormone. Destruction by such a mechanism is rapidly ac- 

 complished by human blood, but not by cerebrospinal fluid. 

 About 0.025-0.05 unit per cc. of blood is thus inactivated 

 after 1.5-2 hours (see also Jones and Schlapp, 1936; and 

 Heller, 1937). 



'7 See also pp. 265-66, 278-79. 



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