title: Synergistic effects of H2O2 with components of dental restorative materials on gluconeogenesis in rat kidney tubules.
abstract: No data are available about (toxic) effects of dental materials administered in combination with H(2)O(2) from dental bleaching compounds. The effect of dental composite components triethyleneglycoldimethacrylate (TEGDMA) and hydroxyethylmethacrylate (HEMA) as well as mercuric chloride (HgCl(2)) and methylmercury chloride (MeHgCl), each in combination with H(2)O(2), was investigated on gluconeogenesis in kidney cells. From rats kidney tubules were prepared. Every 10 min up to 60 min 1-ml samples were drawn from the cell suspension for quantitating the glucose content. Glucose formation in controls was 3.5+/-0.3 nmol/mg.per min (mean+/-SEM, n=21). Relative rates of glucose formation were obtained by expressing individual rates as percentage of the corresponding control. X-Y concentration curves (effective concentration, EC) of the substances were calculated by fitting a four-parametric sigmoid function to the relative rates of the glucose formation at various test concentrations. At the end of the incubation period cell viability was assessed by trypan blue exclusion. Cell viability decreased within the 60 min interval from 90% to approx. 80% (controls), <25 (HEMA), <20 (TEGDMA), <20 (H(2)O(2)) <10 (MeHgCl), and <10 (HgCl(2)). Values of 50% effective concentration (EC(50)) were calculated from fitted curves. EC(50) values were (mmol/l; mean+/-SEM; n=4): HEMA, 17.2+/-2.8; TEGDMA, 1.9+/-0.2; H(2)O(2) 0.22+/-0.03, MeHgCl, 0.016+/-0.0005; and HgCl(2), 0.0017+/-0.0005. No significant decrease of the EC(50) values was found when kidney cells were exposed to HEMA, HgCl(2), or MeHgCl in addition with H(2)O(2) (1-100 microM), compared to those EC(50) values of each compound without H(2)O(2) addition. A significant decrease of the TEGDMA EC(50) values to about 0.25 or 0.04 (mmol/l) was found when cells were exposed to TEGDMA in combination with H(2)O(2) (75 or 100 microM), compared to that TEGDMA EC(50) value without H(2)O(2) addition. The addition of H(2)O(2) (75 and 100 microM) resulted in a synergistic toxic effect of TEGDMA.
authors.affiliation: Walther-Straub-Institute of Pharmacology and Toxicology, Ludwig-Maximilians-University of Munich, Nussbaumstr. 26, 80336, Munich, Germany. reichl@lmu.de
authors.forename: Reichl
authors.initials: R
authors.lastname: Franz-Xaver
authors.forename: Durner
authors.initials: D
authors.lastname: Jürgen
authors.forename: Kehe
authors.initials: K
authors.lastname: Kai
authors.forename: Folwaczny
authors.initials: F
authors.lastname: Matthias
authors.forename: Kleinsasser
authors.initials: K
authors.lastname: Norbert
authors.forename: Schwarz
authors.initials: S
authors.lastname: Markus
authors.forename: Karim
authors.initials: K
authors.lastname: El-Mahdy
authors.forename: Hickel
authors.initials: H
authors.lastname: Reinhard
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003764:Dental Materials / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005943:Gluconeogenesis / Q000187:drug effects*; D006861:Hydrogen Peroxide / Q000633:toxicity*; D007684:Kidney Tubules / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008627:Mercuric Chloride / Q000633:toxicity; D008689:Methacrylates / Q000633:toxicity; D008767:Methylmercury Compounds / Q000633:toxicity; D011092:Polyethylene Glycols / Q000633:toxicity; D011109:Polymethacrylic Acids / Q000633:toxicity; D051381:Rats
chemical_list: D003764:Dental Materials; D008689:Methacrylates; D008767:Methylmercury Compounds; D011109:Polymethacrylic Acids; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D008627:Mercuric Chloride; C005044:hydroxyethyl methacrylate; D006861:Hydrogen Peroxide; C004925:methylmercuric chloride