SODIUM-POTASSIUM ADENOSINE-TRIPHOSPHATASE ALPHA-SUBUNIT AND ALPHA-SUBUNIT MESSENGER-RNA LEVELS IN EARLY RABBIT EMBRYOS

Sodium/potassium adenosine triphosphatase (Na+/K+ ATPase) and Na+/K+ ATPase mRNA content of rabbit embryos during preimplantation development were evaluated. Changes in Na+/K+ ATPase α-subunit content were detected with Western blotting using polyclonal antiserum against guinea pig Na+/K+ ATPase. Total RNA samples from rabbit embryos were analyzed by using Northern 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 kilobases) in sheep kidneys and rabbit embryos. Between Day 4 and Day 6 of development, Na+/K+ ATPase α-subunit mRNA content increased 35-fold whereas Na+/K+ ATPase α-subunit content increased 22-fold. The similar increase in Na+/K+ ATPase α-subunit mRNA and α-subunit content in rabbit embryos suggests that Na+/K+ ATPase is partly regulated at the mRNA level during blastocyst expansion.