Normal and hypophysectomized rats were used in order to observe effects of hypophysectomy on concentration or distribution of water and electrolytes in plasma and various tissues, such as liver, skeletal muscle, cardiac muscle, kidney and brain. 10 of normal rats were used as a control group (first group) and 20 of hypophysectomized rats were divided into 4 groups and were sacrificed as follows; second group was sacrificed 2 days after hypophysectomy, third group was 4 days, fourth group was 6 days and fifth group was 8 days after hypophysectomy.
Daily change of urine volume and excretory rates of sodium and potassium were also measured for a period of 8 days after hypophysecetomy in each group of hypophysectomized rats.
Data obtained were as follows;
1. The mean urine volume of control group was 5.4±2.1 ㏄／day, but the urine volume increased atout 10 times of control value at 2 days after hypophysectomy. Thereafter, the urine volumes were decreased remarkably according to the time elapsed. However, this value still showed tbout 3 times of control even in the fifth group.
The mean sodium excretion was 1.4±0.5mEq／day in the control group. These values were initially high showing 2.4±0.7 mEq／day in the secand group, but decreased thereafter to the same order of control value at the period of 8 days after hypophysectomy (fifth group). While, potassium excretiors were slightly increased after hypophysectomy.
2. Mean plasma concentrations of sodium were 151.2±2.3 mEq／l in the control, 145.2±4.5 mEq／l in the second group, 140.3±3.5 mEq／l in the third group, 138.4±5.6 mEq／l in the fourth group and 139.6±4.7 mEq／l in the fifth group. These values always showed lower values in the hypophysectomized groups than in the control group. On the other hand, plasma concentrations of potassium in the hypophysectomized groups were always higher than that in the control.
3. Variations of distributions of water, sodium and potassium in various tissues after hypophysectomy were as follows;
Total tissue waters were slightly increased in the liver, skeletal muscle and cardiac muscle. However, there were a little changes in kidney and brain tissues as compared with control value.
Tissue concentrations of sodium and potassium showed always slightly lower values after hypophysectomy than those in the control, but tissue concentration of potassium was tend to increase, approaching to the control, according to the time elapsed after hypophysectomy, even though this value never be reached to the control value. Variations in tissue concentrations of sodium and potassium in the brain tissue were negligible.
Extracellular fluid (ECF), determined by sodium space in various tissues, decreased, but intracellular fluids (ICF) were slightly increased after hypophysectomy.
Total sodium and potassium conrentrations in tissue water and ICF water were initially decreased, but tend to approach to control value according to the time elapssd after hypophysectomy except in the brain tissue.
From the above data, it is concluded that hypophysectomized rats were characterized by low electrolytes distribution both in the tissue water and ICF water, decrease in ECF and slight increase in ICF, and total tissue water, even though hypophysectomy does not cause fetal damage in their distribution of water and electrolytes.
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