THE EFFECTS OF OESTRADIOL ON THE RAT UTERUS

Abstract

1. The water and electrolyte changes in the uteri of spayed rats have been investigated after the administration of oestradiol-17 (β) and are found to fall into two main phases. 2. 6–10 hr. after the subcutaneous injection of the hormone the total water content increases, as a result of expansion of the extracellular fluid space and of the relative cell volume. The increase of the relative cell volume is caused by an increase of the idiomolar value. 3. 18–54 hr. after the injection the total water content increases again after a temporary fall. The water increase is now confined to the intracellular space. Total nucleoprotein and residual phosphorus increase, and it is suggested that the nucleoprotein phosphate groups are responsible for the increase of the electrostatic equivalent and hence the increased potassium concentration in the cells. The idiomolar value falls, and there is probably an increased formation of cell protein at this stage. 4. The changes observed in the total water content of the organ agree with the findings of Astwood [1938], Talbot, Lowrie & Astwood [1940] and Zuckerman, Palmer & Hanson [1950]. There are no significant changes in the plasma concentrations of potassium, sodium or chloride or in the total osmotic pressure of the plasma.