Cell volume kinetics of adherent epithelial cells measured by laser scanning reflection microscopy: determination of water permeability changes of renal principal cells

Item Type:	Article
Title:	Cell volume kinetics of adherent epithelial cells measured by laser scanning reflection microscopy: determination of water permeability changes of renal principal cells
Creators Name:	Maric, K. and Wiesner, B. and Lorenz, D. and Klussmann, E. and Betz, T. and Rosenthal, W.
Abstract:	The water channel aquaporin-2 (AQP2), a key component of the antidiuretic machinery in the kidney, is rapidly regulated by the antidiuretic hormone vasopressin. The hormone exerts its action by inducing a translocation of AQP2 from intracellular vesicles to the cell membrane. This step requires the elevation of intracellular cyclic AMP. We describe here a new method, laser scanning reflection microscopy (LSRM), suitable for determining cellular osmotic water permeability coefficient changes in primary cultured inner medullary collecting duct (IMCD) cells. The recording of vertical-reflection-mode x-z-scan section areas of unstained, living IMCD cells proved useful and valid for the investigation of osmotic water permeability changes. The time-dependent increases of reflection-mode x-z-scan section areas of swelling cells were fitted to a single-exponential equation. The analysis of the time constants of these processes indicates a twofold increase in osmotic water permeability of IMCD cells after treatment of the cells both with forskolin, a cyclic AMP-elevating agent, and with Clostridium difficile toxin B, an inhibitor of Rho proteins that leads to depolymerization of F-actin-containing stress fibers. This indicates that both agents lead to the functional insertion of AQP2 into the cell membrane. Thus, we have established a new functional assay for the study of the regulation of the water permeability at the cellular level.
Keywords:	Actins, Bacterial Proteins, Bacterial Toxins, Cell Line, Cyclic AMP, Forskolin, Kidney, Kinetics, Confocal Microscopy, Fluorescence Microscopy, Osmosis, Tertiary Protein Structure, Protein Transport, Time Factors, Water, Animals, Dogs, Rats
Source:	Biophysical Journal
ISSN:	0006-3495
Publisher:	Biophysical Society
Volume:	80
Number:	4
Page Range:	1783-1790
Date:	April 2001
Official Publication:	https://doi.org/10.1016/S0006-3495(01)76148-6
PubMed:	View item in PubMed

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