SODIUM-POTASSIUM ADENOSINE-TRIPHOSPHATASE ALPHA-SUBUNIT AND BETA-SUBUNIT AND ALPHA-SUBUNIT MESSENGER-RNA LEVELS DURING MOUSE EMBRYO DEVELOPMENT INVITRO

Changes in sodium/potassium adenosine triphosphate (Na+/K+ ATPase) and Na+/K+ ATPase mRNA content during preimplantation mouse embryo development were determined. Western blotting, using polyclonal antiserum against guinea pig Na+/K+ ATPase, was used to detect changes in Na+/K+ ATPase α- and β-subunit content during mouse embryo development. Total RNA from mouse embryos was analyzed using Northern and slot blots hybridized with random-primer-labeled cDNA for Na+/K+ ATPase α-subunit from sheep kidney. Northern blots exhibited a single mRNA band (3.65 kb) in sheep and mouse kidneys and mouse embryos. Although Na+/K+ ATPase α-subunit mRNA content of mouse embryos increased 45-fold between Day 1 and Day 4 of development, Na+/K+ ATPase α-subunit content remained constant, and β-subunit content increased 9-fold. The Na+/K+ ATPase α-subunit and α-subunit mRNA content did not increase in a similar manner. The results suggest that, in mouse embryos, blastocoel formation is not triggered by an increase in Na+/K+ ATPase α-subunit content. Changes in β-subunit content may be important in regulating Na+/K+ ATPase activity in and blastocoel formation.