Water, electrolyte, glycogen, and histamine content of rat uterus during pregnancy.

Abstract

Changes in uterine and placental constituents were studied during pregnancy in the rat. Amounts of H2O, Na, Cl, K, glycogen, and histamine were determined at 3-day intervals throughout gestation. The most dramatic changes were observed in the concentrations of glycogen and histamine. Interdecidual tissue showed a fivefold increase in glycogen from day 9 to 21. Histamine decreased steadily in this tissue until at term there was less than half the initial value. Both fetal and maternal placenta contained more H2O than interdecidual uterus, and electrolytes were lower. Maternal placental tissues showed marked H2O depletion on day 15 but returned to former levels subsequently. The K level of the fetal placenta decreased sharply at term. Cl and Na in placental tissues were low at day 15. Glycogen in maternal placenta quadrupled during the last 8 days, whereas glycogen in fetal placenta diminished to one-third its earlier value. Histamine content of the fetal placenta increased during the last half of pregnancy.