Mechanisms of [Ca2+]i elevation by H2O2 in islets of rats.
Activity of reactive oxygen species is elevated in diabetes mellitus and has been implicated in the destruction of cellular components. The toxic effect of reactive oxygen species was investigated by testing the effect of H2O2 on [Ca2+]i in isolated islets of Langehans. H2O2 increased [Ca2+]i in a dose-dependent manner, which was irreversible at high concentrations. The maximum effect of H2O2 on [Ca2+]i was larger than those of KCl, glucose, ATP, carbachol and endothelin-1. The effect of H2O2 was only partially attenuated by removal of external Ca2+ and by the in-organic Ca2+ channel blocker nickel, but was not blocked by voltage-dependent or -independent Ca2+ channel blockers nimodipine, nicardipine, SK&F 96365, econazole and lanthanum. H2O2, disrupted [Ca2+]i homeostasis in islets by affecting both release and influx of Ca2+ and causing dysfunction of Ca2+ clearance systems and may contribute to the pathological process of diabetes.
Tang
J
J
Department of Physiology & Biophysics, The University of Mississippi Medical Center, Jackson 39216, USA.
Zhang
J H
JH
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D005456:Fluorescent Dyes; D005470:Fluorometry; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D066298:In Vitro Techniques; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism
D005456:Fluorescent Dyes; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D002118:Calcium