(Na+-K+)-ATPase activities in rat tissues during pregnancy.

(Na+-K+)-ATPase activities of liver, hind leg skeletal muscle, brain, perirenal white adipose tissue, interscapular brown adipose tissue and blood as well as placenta, fetal liver and fetal blood were determined in virgin rats and pregnant rats on days 12, 19 and 21 of gestation in order to evaluate its relative contribution either to metabolite transport processes or/and to thermogenesis during pregnancy. No changes were found in (Na+-K+)-ATPase activity in liver, blood and white adipose tissue in pregnant rats versus controls. (Na+-K+)-ATPase activity from muscle, brain and interscapular brown adipose tissue decreased during pregnancy and placenta showed an increase of (Na+-K+)-ATPase on day 21 of gestation in respect to day 12. No significant changes were observed either in fetal liver or fetal blood.