Vanadate-activated calcium influx in A431 cells is dependent on the plasma membrane potential
✍ Scribed by Ian G. Macara; George M. Gray
- Publisher
- John Wiley and Sons
- Year
- 1987
- Tongue
- English
- Weight
- 229 KB
- Volume
- 34
- Category
- Article
- ISSN
- 0730-2312
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✦ Synopsis
Vanadate can activate the uptake of Ca in A43 1 epidermal carcinoma cells by twoto fivefold with no detectable lag period. Preincubation with epidermal growth factor (EGF) to down-regulate the EGF receptor prevents subsequent stimulation by EGF but not that by vanadate. Ca uptake is sodium-independent and is not activated by depolarization in high KCl. On the contrary, vanadate-stimulated uptake is completely inhibited by decreasing the plasma membrane potential from about -65 to -30 mV. These results demonstrate that the EGF receptor is not itself functioning as a Ca channel, that vanadate is not acting at the level of EGF receptor, and that the Ca transport system exhibits an unusual potential sensitivity in that it is inhibited by depolarization of the plasma membrane.