title: Changes in extra- and intracellular pH in hepatocytes exposed to gabexate mesilate.
abstract: Gabexate mesilate (GM) is a synthetic inhibitor of plasmatic and pancreatic serine proteases licensed for the treatment of pancreatitis. Here we show that in suspensions of isolated hepatocytes, profound changes in extracellular, cytoplasmic, and vesicular pH occur after addition of GM. Isolated hepatocytes obtained by collagenase perfusion of rat liver were pre-incubated with 1, 2, and 4 mM GM. Extracellular pH (pH in the incubation medium) was measured by a conventional pH electrode, cytosolic and vesicular pH were measured by fluorescence changes of 2',7'-biscarboxyethyl-5,6-carboxyfluorescein acetoxymethyl ester (BCECF-AM) and fluorescein dextran, respectively. Incubation of hepatocytes with GM resulted in a dose-dependent decrease of extracellular pH. Cytosolic pH decreased rapidly and markedly in a dose-dependent manner during the first minutes and gradually returned towards baseline. Simultaneously, GM induced a rapid alkalinization of acidic vesicles. The presence of bis-(p-nitrophelyl) phosphate (BNPP), an esterase inhibitor, reduced the extent of extracellular acidification. Incubation of hepatocytes in the presence of dimethylamiloride, an Na+/H+ exchanger inhibitor, or in a sodium-free medium, did not modify the rate and extent of extracellular acidification. GM, a commercially available pharmacological agent, could be useful to manipulate extra- and intracellular pH.
authors.affiliation: Scientific Directorate, University of Pavia, Pavia, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Imberti
authors.affiliation: Department of Internal Medicine and Therapeutics, University of Pavia, Pavia, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Ferrigno
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, University of Pavia, Pavia, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Tartaglia
authors.affiliation: Department of Molecular Medicine, University of Pavia and Foundation IRCCS Policlinico S. Matteo, University of Pavia, Pavia, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Rizzo
authors.affiliation: Department of Internal Medicine and Therapeutics, University of Pavia, Pavia, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Richelmi
authors.affiliation: Department of Internal Medicine and Therapeutics, University of Pavia, Pavia, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Vairetti
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D016670:Gabexate / Q000494:pharmacology*; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008297:Male; D008698:Mesylates / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology*
chemical_list: D008698:Mesylates; D015842:Serine Proteinase Inhibitors; C045880:methanesulfonic acid; D016670:Gabexate