title: Effect of oxidative stress on cellular functions and cytosolic free calcium of rat pancreatic acinar cells.
abstract: The present study evaluates the effect of free radicals generated by xanthine oxidase-catalyzed oxidation of hypoxanthine on cellular function of isolated rat pancreatic acinar cells. The results show that a rapid and sustained increase in intracellular Ca2+ concentration ([Ca2+]i) preceded all other morphological and functional alterations investigated. Radical-induced [Ca2+]i increase was largely inhibited by 3,4,5-trimethoxybenzoic acid 8-(diethylamino)octyl ester, which prevents Ca2+ release from intracellular stores, but not by Ca2(+)-depleted medium. Radicals released Ca2+ from thapsigargin-insensitive, ryanodine-sensitive intracellular stores, whereas the secretagogue caerulein at physiological concentrations mainly released Ca2+ from thapsigargin-sensitive stores. In contrast to effects of the secretagogue, radical-induced Ca2+ changes did not cause luminal protein secretion but cell death. In single-cell measurements, both secretagogue and radicals induced oscillations of [Ca2+]i. Radical-induced oscillations had a lower frequency but similar amplitude when compared with caerulein-induced oscillations. 1,2-Bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid and ryanodine, which prevented the radical-induced Ca2+ increase without altering the generation of radicals, markedly reduced the radical-induced cell damage. These results suggest that the Ca2+ increase mediates the radical-induced cell injury. The studies also indicate that not only the extent and duration but also the origin of [Ca2+]i release as well as the frequency of Ca2+ oscillations may determine whether a pancreatic acinar cell will secrete or die.
authors.affiliation: Department of Medicine, Heinrich-Heine-University of Düsseldorf, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Klonowski-Stumpe
authors.forename: R
authors.initials: R
authors.lastname: Schreiber
authors.forename: M
authors.initials: M
authors.lastname: Grolik
authors.forename: H U
authors.initials: HU
authors.lastname: Schulz
authors.forename: D
authors.initials: D
authors.lastname: Häussinger
authors.forename: C
authors.initials: C
authors.lastname: Niederau
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000681:Amylases; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002108:Ceruletide / Q000494:pharmacology; D002712:Chlorides; D003600:Cytosol / Q000378:metabolism; D004492:Edetic Acid / Q000494:pharmacology; D005290:Ferric Compounds / Q000494:pharmacology; D005609:Free Radicals / Q000378:metabolism; D019271:Hypoxanthine / Q000494:pharmacology; D007700:Kinetics; D007770:L-Lactate Dehydrogenase; D008297:Male; D018384:Oxidative Stress; D010179:Pancreas / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012433:Ryanodine / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D014969:Xanthine Oxidase / Q000378:metabolism
chemical_list: D002712:Chlorides; D005290:Ferric Compounds; D005609:Free Radicals; D012433:Ryanodine; D019271:Hypoxanthine; D000001:Calcimycin; D019284:Thapsigargin; D002108:Ceruletide; D000255:Adenosine Triphosphate; D004492:Edetic Acid; D007770:L-Lactate Dehydrogenase; D014969:Xanthine Oxidase; D000681:Amylases; D002118:Calcium; C024555:ferric chloride