Abstract
The aim of this study was to determine whether extracellular ATP ([ATP]o) stimulated a Ca2+-activated K+ efflux in trophoblast cells that was dependent on extracellular Ca2+ ([Ca2+]o). Cytotrophoblast cells, isolated from human placenta, were examined following 18 h (relatively undifferentiated) and 66 h (multinucleate cells) of culture. Potassium efflux was measured using 86Rb as a trace marker. Intracellular Ca2+ ([Ca2+]i) was examined by microfluorometry using fura 2. [ATP]o significantly increased 86Rb efflux to a peak that declined to control (18-h cells) or an elevated plateau (66-h cells) and was inhibited by 100 nM charybdotoxin. Removing [Ca2+]o significantly reduced 86Rb efflux in both groups as did application of 150 μM GdCl3. [ATP]o significantly increased [Ca2+]i in both groups of cells. The response was reduced by removing [Ca2+]o and applying 150 μM GdCl3. For both 86Rb efflux and microfluorometry experiments, the response to [ATP]o was more dependent on [Ca2+]o in 66-h cells compared with 18-h cells (∼70% greater). Cytotrophoblast cells exhibit an [ATP]o-stimulated Ca2+-activated K+ efflux. The dependency of this pathway on [Ca2+]o is greater in the 66-h multinucleate syncytiotrophoblast-like cells, suggesting that the mechanism for Ca2+ entry may be altered during differentiation of trophoblast cells.
Original language | English (US) |
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Pages (from-to) | R1077-R1085 |
Journal | American Journal of Physiology - Regulatory Integrative and Comparative Physiology |
Volume | 282 |
Issue number | 4 51-4 |
DOIs | |
State | Published - 2002 |
Externally published | Yes |
Keywords
- Calcium entry
- Human placenta
- Intermediate calcium-activated potassium channel
ASJC Scopus subject areas
- Physiology
- Physiology (medical)