title: Ouabain-induced cytoplasmic vesicles and their role in cell volume maintenance.
abstract: Cellular swelling is controlled by an active mechanism of cell volume regulation driven by a Na(+)/K(+)-dependent ATPase and by aquaporins which translocate water along the osmotic gradient. Na(+)/K(+)-pump may be blocked by ouabain, a digitalic derivative, by inhibition of ATP, or by drastic ion alterations of extracellular fluid. However, it has been observed that some tissues are still able to control their volume despite the presence of ouabain, suggesting the existence of other mechanisms of cell volume control. In 1977, by correlating electron microscopy observation with ion and water composition of liver slices incubated in different metabolic conditions in the presence or absence of ouabain, we observed that hepatocytes were able to control their volume extruding water and recovering ion composition in the presence of ouabain. In particular, hepatocytes were able to sequester ions and water in intracellular vesicles and then secrete them at the bile canaliculus pole. We named this "vesicular mechanism of cell volume control." Afterward, this mechanism has been confirmed by us and other laboratories in several mammalian tissues. This review summarizes evidences regarding this mechanism, problems that are still pending, and questions that need to be answered. Finally, we shortly review the importance of cell volume control in some human pathological conditions.
authors: Laboratory of Molecular and Cellular Pathology, IRCCS San Raffaele Pisana, Via di Val Cannuta 247, 00166 Roma, Italy.
authors: M A
authors: MA
authors: Russo
authors: Department of Experimental Medicine, Sapienza University of Rome, 00161 Rome, Italy.
authors: E
authors: E
authors: Morgante
authors: IRCCS Regina Elena Institute, 00144 Rome, Italy.
authors: A
authors: A
authors: Russo
authors: Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA.
authors: G D
authors: GD
authors: van Rossum
authors: Laboratory of Molecular and Cellular Pathology, IRCCS San Raffaele Pisana, Via di Val Cannuta 247, 00166 Roma, Italy ; Department of Experimental Medicine, Sapienza University of Rome, 00161 Rome, Italy.
authors: M
authors: M
authors: Tafani
mesh_terms: D000818:Animals; D048429:Cell Size; D022162:Cytoplasmic Vesicles / Q000378:metabolism*; D006801:Humans; D017136:Ion Transport / Q000502:physiology; D010042:Ouabain / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D014882:Water-Electrolyte Balance / Q000502:physiology*
chemical_list: D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase