title: Vacuole formation in mast cells responding to osmotic stress and to F-actin disassembly.
abstract: Fluorescent probes were used to visualize the morphology of membranes and of F-actin in rat peritoneal mast cells, exposed to hyperosmotic medium and consequently reversed to isotonicity. Hypertonicity induced cell shrinkage followed by a regulatory volume increase, and cell alkalinization that was sensitive to amiloride, an inhibitor of the Na(+)/H(+) exchanger (NHE), but not to Latrunculin B, an inhibitor of actin polymerization. Using Bodipy-Sphingomyelin, we have observed formation of vacuole-like dilations (VLDs), primarily at or close to the adhesion plane, following the reversal from hyper- to isotonic medium. VLD formation was not inhibited by Latrunculin B or by amiloride. Phalloidin staining has shown that actin filaments do not surround the vacuoles and latrunculin-induced depolymerization of actin has actually promoted vacuole formation, even in isotonic conditions. The results support the idea that a decrease in membrane tension promotes the internalization of the plasma membrane.
authors.affiliation: Physiology Department, University College London, University Street, London WC1E 6JJ, UK. a.koffer@ucl.ac.uk
authors.forename: Anna
authors.initials: A
authors.lastname: Koffer
authors.forename: Mark
authors.initials: M
authors.lastname: Williams
authors.forename: Torben
authors.initials: T
authors.lastname: Johansen
mesh_terms: D000199:Actins / Q000187:drug effects / Q000378:metabolism*; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D048429:Cell Size / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006982:Hypertonic Solutions / Q000494:pharmacology; D008297:Male; D008407:Mast Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009997:Osmotic Pressure; D011108:Polymers / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors / Q000378:metabolism; D013500:Surface Tension / Q000187:drug effects; D013844:Thiazoles / Q000494:pharmacology; D053778:Thiazolidines; D014617:Vacuoles / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D014882:Water-Electrolyte Balance / Q000502:physiology*
chemical_list: D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D004791:Enzyme Inhibitors; D006982:Hypertonic Solutions; D011108:Polymers; D017923:Sodium-Hydrogen Exchangers; D013844:Thiazoles; D053778:Thiazolidines; D000584:Amiloride; C037068:latrunculin B