| First Author | Solenov E | Year | 2004 |
| Journal | Am J Physiol Cell Physiol | Volume | 286 |
| Issue | 2 | Pages | C426-32 |
| PubMed ID | 14576087 | Mgi Jnum | J:169442 |
| Mgi Id | MGI:4940974 | Doi | 10.1152/ajpcell.00298.2003 |
| Citation | Solenov E, et al. (2004) Sevenfold-reduced osmotic water permeability in primary astrocyte cultures from AQP-4-deficient mice, measured by a fluorescence quenching method. Am J Physiol Cell Physiol 286(2):C426-32 |
| abstractText | A calcein fluorescence quenching method was applied to measure osmotic water permeability in highly differentiated primary cultures of brain astrocytes from wild-type and aquaporin-4 (AQP-4)-deficient mice. Cells grown on coverglasses were loaded with calcein for measurement of volume changes after osmotic challenge. Hypotonic shock producing twofold cell swelling resulted in a reversible approximately 12% increase in calcein fluorescence, which was independent of cytosolic calcein concentration at levels well below where calcein self-quenching occurs. Calcein fluorescence was quenched in <200 ms in response to addition of cytosol in vitro, indicating that the fluorescence signal arises from changes in cytosol concentration. In astrocytes from wild-type CD1 mice, calcein fluorescence increased reversibly in response to hypotonic challenge with a half-time of 0.92 +/- 0.05 s at 23 degrees C, corresponding to an osmotic water permeability (Pf) of approximately 0.05 cm/s. Pf was reduced 7.1-fold in astrocytes from AQP-4-deficient mice. Temperature dependence studies indicated an increased Arrhenius activation energy for water transport in AQP-4-deficient astrocytes (11.3 +/- 0.5 vs. 5.5 +/- 0.4 kcal/mol). Our studies establish a calcein quenching method for measurement of cell membrane water permeability and indicate that AQP-4 provides the principal route for water transport in astrocytes. |
