Effects of Pregnancy on the Contents of Water, Taurine, and Total Amino Nitrogen in Rat Cerebral Cortex

: Plasma osmolality and the levels of water, taurine, and total amino nitrogen (detected as ninhydrin‐positive substances) have been measured in the cerebral cortices of nonpregnant and 19‐day pregnant Wistar rats. Plasma osmolality fell by 11 mosmol/kg during pregnancy. Brain water content remained unaltered, but levels of taurine and ninhydrin‐positive substances fell by 48.5 and 21.9%, respectively. It is suggested that one way in which brain cells are prevented from swelling during the mild hypoosmolality of pregnancy is through loss of cellular amino nitrogen, particularly taurine.