Effect of estrogen and progesterone on water and electrolyte content of rabbit uteri

¹ U.S. Department of Agriculture, Agricultural Research Service, Animal Husbandry Research Division, Beltsville, Maryland

Estrogen, either endogenous or exogenous, caused an uptake of water in the rabbit endometrium. Endometria of rabbits in estrus or of spayed rabbits treated with estrogen had an extracellular compartment which was twice as large as the intracellular phase A similar distribution of water was observed in the endometria of ovariectomized control rabbits. Progesterone caused a complete reversal in the distribution of the endometrial water. Thus, pseudopregnant or progesterone-treated rabbit endometria had an intracellular phase which was twice as large as the extracellular compartment. Changes in Na and K concentrations were associated with these shifts in water between the exterior and interior of the cells. Endometria of progesterone-treated or pseudopregnant rabbits had high K and low Na concentrations in comparison to the estrous, estrogen-treated or ovariectomized rabbit endometria. Expressed as total K/Na ratios, the endometria showed extreme differences, being 0.54 under estrogen domination and 1.38 under progesterone influence.