Effects of Pituitrin Administration on Distribution of Injected Fluid.

Although it is well known that the administration of extracts of the posterior lobe of the pituitary gland may affect blood volume and urine output, there is little agreement as to the mechanism involved. This is due in part to the varying dosages, modes of administration, time of observation, and condition of the experimental animal employed by the various investigators.

The purpose of this investigation was to study the effect of pituitrin administration on the distribution of injected fluid between the blood, urine and tissues. Normal dogs deprived of food and water for 20 hours were used as experimental animals. Ringer's solution was injected intravenously by means of a Woodyatt pump, for a period of two hours, at the rate of either 15 or 25 cc. per kilo body weight per hour. At times, from .05 to .08 cc. of commercial pituitrin (Parke, Davis & Co. or Eli Lilly & Co.) per kilo body weight per hour was added to this solution. Ether was administered by the open cone method in several experiments, in order to study the combined effects of pituitrin and anesthesia. The periods of observation included the two hours of injection and a post-injection period of three hours. Urine was collected by continuous catheterization. Blood was drawn from the jugular vein before, at the end of the injection, and at the close of the post-injection periods. Blood volume increases were calculated from the Hb. and serum protein changes. For comparative purposes 7 per cent of the body weight was considered the average preliminary blood volume. The small volume of urine that the animals would have passed without fluid injection has been neglected in these calculations. The percentage of injected fluid entering the tissues was calculated from the difference between the amount injected and that found to be in the blood and urine.