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Effects of medium calcium, and agents affecting cytoskeletal function, on cellular volume and morphology in liver tissue in vitro
Author(s) -
Russo Matteo A.,
Morgante Emanuela,
Tafani Marco,
van Rossum George D.V.
Publication year - 2012
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.24060
Subject(s) - ouabain , vesicle , biophysics , cytoskeleton , golgi apparatus , microbiology and biotechnology , vacuole , cytoplasm , calcium , biochemistry , osmotic pressure , chemistry , atpase , biology , endoplasmic reticulum , sodium , cell , membrane , enzyme , organic chemistry
The possible role of an exocytotic, vesicular mechanism in cellular volume regulation under iso‐osmotic conditions has been studied in slices of rat liver. The effects of incubation conditions and agents affecting the actin cytoskeleton were examined for changes of water, ionic composition, and ultrastructure. Slices were pre‐incubated at 1°C in an iso‐osmotic buffered medium to induce swelling. Upon restoration to 37°C in the same medium, tissue lost water. The Na + –K + adenosine triphosphatase (ATPase) inhibitor ouabain inhibited water extrusion of about 50%, an effect that was accompanied by the formation of characteristic vesicles in the cytoplasmic region between the Golgi apparatus and the bile canaliculi. Water extrusion in the presence of ouabain was partially inhibited by trifluoroperazine and completely inhibited when the medium was free of Ca 2+ . In the presence of ouabain, brefeldin A caused a small reduction of water extrusion, whereas phalloidin and cytochalasins A, D, or E caused a marked inhibition. In these conditions there was a marked increase in size and number of cytoplasmic vesicles and a more widespread distribution of them within the cells, lacking the more specific orientation to the Golgi and canalicular regions that was seen in the presence of ouabain alone. Water extrusion was inhibited by phalloidin and cytochalasins in the absence of ouabain. In conclusion, our results are consistent with the hypothesis that iso‐osmotic expulsion of water from hepatocytes can proceed partly through an accumulation of water in cytoplasmic vesicles, followed by exocytosis. This mechanism does not depend on Na + –K + ATPase activity. J. Cell. Biochem. 113: 1915–1925, 2012. © 2012 Wiley Periodicals, Inc.