Abstract
A direct action of pituitrin and pitressin on the tissue cells so as to render them incapable of taking up oxygen was one of the possible explanations suggested by Geiling and DeLawder for the significant metabolic changes produced in man and animals by these drugs. 1 , 2 , 3 To test the validity of this suggestion the present work was carried out.
Ahlgren 4 using Thunberg's methylene blue method found that minute concentrations of various posterior pituitary preparations increased tissue respiration. Himwich, Finkelstein and Humphreys, 5 working with the Warburg apparatus, showed on the other hand that the oxygen consumption of excised tissues of white rats is definitely decreased under the influence of pituitrin and pitressin. However, the doses used by them were entirely disproportionate to the amounts generally employed in the intact animal. Accordingly, similar experiments have been carried out with dosages covering a range to include large and small concentrations of post-pituitary preparations (pitressin, pitocin and inactivated pitressin). Even the smallest dose used in this work is relatively large when compared to the effective amount used in the intact dog or in man.
Experimental. White rats weighing approximately 250-300 gm. were used. Liver, heart and diaphragm tissues were excised directly after the animal had been killed by decapitation and their oxygen consumption in the presence of varying quantities of the post-pituitary preparations was immediately determined in Warburg vessels with Barcroft manometers at 37.5°C. 6
Fresh Ringer-buffer-glucose and saline-buffer-glucose solutions, as recommended by Richardson, 7 were used as nutrient media. A thin slice of tissue not more than 0.5 mm. in thickness was placed in the Warburg vessel with 3 cc. of the medium—Ringer-buffer-glucose solution for liver tissue and saline-buffer-glucose solution for diaphragm and heart (ventricle) tissue.
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