Novel bumetanide-sensitive K+ transport in preimplantation mouse conceptuses
| Autor: | L J Van Winkle, Allan L. Campione |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
medicine.medical_specialty
Physiology Michaelis–Menten kinetics Mice Chlorides Internal medicine medicine Animals Channel blocker Blastocyst Amino Acids Ouabain reproductive and urinary physiology Ion transporter Bumetanide Mice Inbred ICR urogenital system Chemistry Furosemide Biological Transport Cell Biology Apical membrane Rubidium Molecular biology Kinetics Endocrinology medicine.anatomical_structure embryonic structures Potassium Cotransporter medicine.drug |
| Zdroj: | The American journal of physiology. 263(4 Pt 1) |
| ISSN: | 0002-9513 |
| Popis: | Ouabain-resistant K+ transport activity was characterized primarily by measuring Rb+ uptake because 86Rb+ has a more convenient half-life than 42K+. Ouabain-resistant 86Rb+ uptake by mouse two-cell conceptuses and blastocysts was slowed by the K(+)-Na(+)-2Cl- cotransporter inhibitors bumetanide [inhibitory constant (Ki) = 400 nM] and furosemide (Ki approximately 10 microM), but it was insensitive to a variety of K+ channel blockers. This component of 86Rb+ transport was also inhibited by K+ and nonradioactive Rb+ and it was stimulated by Cl-. Nevertheless, neither 36Cl- nor 22Na+ uptake was inhibited by bumetanide, whereas 42K+ uptake was inhibited by both bumetanide and furosemide. Bumetanide-sensitive Rb+ transport in blastocysts had a Hill coefficient of 1.0 and a Michaelis constant value of 3.0 mM. By these criteria, preimplantation conceptuses contain a novel, bumetanide-sensitive K+ transport system that does not cotransport Cl- or Na+. Moreover, bumetanide-sensitive Rb+ uptake was 10 times faster in blastocysts when they were collapsed to expose the basal membrane of the trophectoderm to 86Rb+ in the medium. Therefore, the novel system may be located predominantly in the basal rather than in the apical membrane of the trophectoderm. |
| Databáze: | OpenAIRE |
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