THE EFFECT OF POSTERIOR PITUITARY PREPARATIONS UPON THE COLLOID OSMOTIC PRESSURE OF SERUM PROTEIN, WATER AND MINERAL METABOLISM OF DOGS

¹ From the Department of Medicine of the University of Rochester School of Medicine and Dentistry, and the Medical Clinic of the Strong Memorial and Rochester Municipal Hospitals, Rochester, New York

1. Dogs weighing 10 to 18 kgm. were given single subcutaneous injections of 20 to 50 international units of pituitrin and of pitressin.

2. A rather marked hydremia was observed one hour after injection of the pressor hormones.

3. Examination of the blood showed a fall in hematocrit, a decrease in the specific gravity, the refractive index and total protein of serum, and an increase in the plasma volume.

4. The colloid osmotic pressure of the serum changed merely in proportion to the concentration of serum protein.

5. The pressure per gram of protein (specific pressure) showed moderate variations, but these variations were not related to the administration of pituitrin or pitressin. The fact that significant changes in the specific pressure were not observed after the injection of the hormones is evidence against any marked change in the state of molecular aggregation of the serum proteins.

6. During the period of hydremia, the potassium content of the serum increased. It is suggested that the hydremia and increase in the concentration of potassium in the serum were caused by transfer of cell water and potassium to extracellular fluid.