title: Membrane potentials of urinary bladder epithelium in F344 rats treated with N-butyl-N-(4-hydroxybutyl)nitrosamine or sodium saccharin.
abstract: Membrane potentials of the urinary bladder epithelium in F344 male rats treated with N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN) or sodium saccharin were measured. In experiment 1, membrane potentials were measured sequentially in the early stage of their change on treatment with 0.05% BBN in the drinking water or with basal diet containing 5% sodium saccharin. Membrane potentials were measured with microelectrodes in weeks 1, 2, 4 and 8 of the experiment. The potential of the group treated with BBN was significantly higher than that of the controls from as early as week 1 until the end of the experiment. In experiment 2, the dose-dependence of the effects of BBN and sodium saccharin on the membrane potential was examined. F344 male rats were treated with 0.05, 0.01, 0.005 or 0.001% BBN in the drinking water, or 5, 1, 0.2 or 0.04% sodium saccharin in basal diet. Clear dose-dependence was observed in the effect of BBN on the potential, but of the doses of sodium saccharin used, only 5% saccharin caused a significantly higher potential than in the control group. These findings suggested that in the early stage of urinary bladder carcinogenesis induced by BBN, the Na+ channel located in the apical membrane may be inactivated.
mesh_terms: D000818:Animals; D002085:Butylhydroxybutylnitrosamine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004848:Epithelium / Q000187:drug effects / Q000502:physiology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009602:Nitrosamines / Q000494:pharmacology*; D051381:Rats; D011916:Rats, Inbred F344; D012439:Saccharin / Q000494:pharmacology*; D001743:Urinary Bladder / Q000187:drug effects / Q000502:physiology*
chemical_list: D009602:Nitrosamines; D002085:Butylhydroxybutylnitrosamine; D012439:Saccharin