Abstract
The influence of posterior pituitary extracts on mineral and water exchange was studied in 2 boys aged 9 and 5 years. The environmental and metabolic conditions, except for changes induced during experimental periods, were kept as constant as possible throughout the study. Each day was divided into 4 six-hour periods beginning at 6:00 A.M. At the beginning of each period, the subject voided, was weighed, and then given an accurately prepared meal of known weight and composition. The 4 meals of the day were identical in every respect and were prepared from simple foods of relatively constant mineral content. Water balances were calculated by the method suggested by Newburgh, Johnston and Falcon-Lesses. 1 On ashed urine sodium was determined by the uranyl acetate method of Barber and Kolthoff 2 and potassium by the chloroplastinate method of Shohl and Bennett. 3 In view of the short periods utilized, mineral excretion in the stool was disregarded and average urinary excretion on control periods was used as a base line for determining fluctuations from normal during experimental periods. The posterior pituitary preparation pitressin was administered in all instances by the subcutaneous route.
The results of the 2 experiments presented in Table I clearly demonstrate that pitressin has a pronounced effect on mineral as well as water exchange.
The retention of water during the period of antidiuresis is associated with a large increase in urinary sodium and chlorid excretion. Potassium output is diminished in one experiment but is unaltered in 2 other studies. The effect of pitressin lasts about 3 hours after the last injection and is followed by an enormous water loss, exceeding the storage of the antidiuretic period by several hundred grams. The increased sodium and chlorid excretion persists throughout the period of diuresis.
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