Effect of Pituitrin Administration on Rate of Disappearance of Injected Substances.

Abstract

In previous investigations by the authors, 1 , 2 it was found that pituitrin administration resulted in a decreased rate of removal of injected fluid and glucose by the tissues of the unanesthetized dog. This report is concerned with the effect of pituitrin on the removal from the blood stream of intravenously injected chlorides and a colloidal dye, Brilliant Vital Red. The former is of interest because the work of other investigators tended to show that the diuretic-antidiuretic action of pituitrin may be due to an effect on electrolyte distribution.

Unanesthetized dogs deprived of food and water for a period of 20 hours were injected with an isotonic or hypertonic (5 times isotonic) Ringer's solution at a rate of 15 or 25 cc. per kilo body weight per hour by the continuous intravenous method. At times commercial pituitary extracts in amounts of .05 to .08 cc. per kilo per hour were added to this solution. Studies were made of plasma chloride changes, chloride output in urine and relative blood volume changes as calculated from hemoglobin and plasma protein changes. The amount of chlorides retained by the tissues was calculated from the difference between the amount injected and that present in urine and blood. The small amount of chlorides that the animal would have eliminated without chloride administration has been neglected in these calculations. The effect of pituitrin on rate of disappearance of Brilliant Vital Red from the blood was determined by comparing the plasma dye concentration following the injection of 15 mg. per kilo of body weight at intervals of 1/10, 1½, 3½, 6 and 9 hrs. after its administration. Controls were run on all animals and the order of the control and pituitrin experiments was alternated in the different animals.