Association of vanadate-sensitive Mg2+-ATPase and shape change in intact red blood cells
✍ Scribed by Y.-H. Xu; Z.-Y. Lu; A. D. Conigrave; M. E. Auland; B. D. Roufogalis
- Publisher
- John Wiley and Sons
- Year
- 1991
- Tongue
- English
- Weight
- 567 KB
- Volume
- 46
- Category
- Article
- ISSN
- 0730-2312
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✦ Synopsis
Abstract
Intact human erythrocytes, initially depleted of Mg^2+^ by EDTA incubation in the presence of A23187, exhibit Mg^2+^‐dependent phosphate production of around 1.5 mmol per liter cells · h, half‐maximally activated at around 0.4 mM added free Mg^2+^. This appears to correspond to Mg^2+^‐stimulated adenosine triphosphatase (Mg^2+^‐ATPase) activity found in isolated membranes, which is known to have a similar activity and affinity for Mg^2+^. Vanadate (up to 100 μM) inhibited Mg^2+^‐dependent phosphate production and ATP breakdown in intact cells. Over a similar concentration range vanadate (3–100 μM) transformed intact cells from normal discocytes to echinocytes within 4–8 h at 37°C, and more rapidly in Mg^2+^‐depleted cells. The rate of Ca^2+^‐induced echinocytosis was also enhanced in Mg^2+^‐depleted cells. These results support previous studies in erythrocyte ghosts suggesting that vanadate‐induced shape change is associated with inhibition of Mg^2+^‐ATPase activity localized in the plasma membrane of the red blood cell.