Ouabain-sensitive Rb+ uptake in mouse eggs and preimplantation conceptuses

Journal Article · Mon Jul 01 04:00:00 EDT 1991 · Developmental Biology; (United States)

DOI:https://doi.org/10.1016/0012-1606(91)90456-D· OSTI ID:5464127

Van Winkle, L J; Campione, A L ^[1]

---

1. Department of Biochemistry, Chicago College of Osteopathic Medicine, Downers Grove, IL (USA)

The results of histochemical and immunocytochemical studies have been used elsewhere to support the hypothesis that Na+/K(+)-ATPase expression is initiated or increases dramatically in preimplantation mouse conceptuses just before they begin to cavitate. Moreover, localization of the enzyme in the inner membrane of the mural trophoblast is thought to be involved directly in formation and maintenance of the blastocyst cavity. Presumably, Na+/K(+)-ATPase extrudes the cation, Na+, and therefore water into the cavity. The cation transporting activity of the enzyme can be determined by measuring ouabain-sensitive Rb+ uptake by cells. Therefore, we measured Rb+ uptake in mouse eggs and preimplantation conceptuses at various stages of development. 86Rb+ uptake by conceptuses increased linearly with time for at least 60 min in medium containing 0.7 mM total Rb+ plus K+ in the absence or presence of 1.0 mM ouabain, and ouabain inhibited more than 70% of 86Rb+ uptake. The ouabain concentration at 1/2 of maximum inhibition of the ouabain-sensitive component of 86Rb+ uptake was about 10-20 microM in eggs and conceptuses at all stages of preimplantation development. Moreover, ouabain-sensitive Rb+ uptake had a twofold higher Vmax value in blastocysts than in eggs or conceptuses at earlier stages of development (i.e., approximately 173 vs 70-100 fmole.conceptus-1.min-1), although the total cell surface area also was probably about two times greater in blastocysts than in eggs or other conceptuses. Ouabain-sensitive Rb+ transport in eggs and conceptuses may have occurred via a single ouabain-sensitive Rb+ transporter with a Hill coefficient of 1.5-1.8 (Hill plots). When it was assumed that the Hill coefficient had a value of 2.0, however, eggs and conceptuses appeared to contain at least two forms of Na+/K(+)-ATPase activity.

• OSTI ID: 5464127
• Journal Information: Developmental Biology; (United States), Journal Name: Developmental Biology; (United States) Vol. 146:1; ISSN 0012-1606; ISSN DEBIA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ACID ANHYDRASES
ALKALI METAL COMPOUNDS
ANIMALS
ATP-ASE
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOHYDRATES
CARDIAC GLYCOSIDES
CARDIOTONICS
CARDIOVASCULAR AGENTS
CATIONS
CHARGED PARTICLES
DAYS LIVING RADIOISOTOPES
DRUGS
EGGS
ELECTRON CAPTURE RADIOISOTOPES
ENZYME ACTIVITY
ENZYMES
GLYCOSIDES
HYDROLASES
INTERMEDIATE MASS NUCLEI
IONS
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
MEMBRANE TRANSPORT
MICE
MINUTES LIVING RADIOISOTOPES
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
OUABAIN
PHOSPHOHYDROLASES
PREGNANCY
RADIOISOTOPES
RODENTS
RUBIDIUM 86
RUBIDIUM COMPOUNDS
RUBIDIUM ISOTOP
SODIUM COMPOUNDS
STROPHANTHINS
TRACER TECHNIQUES
VERTEBRATES