Hydrogen peroxide modulates K+ ion currents in cultured Aplysia sensory neurons.
Hydrogen peroxide (H(2)O(2)) causes oxidative stress and is considered a mediator of cell death in various organisms. Our previous studies showed that prolonged (>6 h) treatment of Aplysia sensory neurons with 1 mM H(2)O(2) produced hyperpolarization of the resting membrane potential, followed by apoptotic morphological changes. In this study, we examined the effect of H(2)O(2) on the membrane conductance of Aplysia sensory neurons. Hyperpolarization was induced by 10 mM H(2)O(2) within 1 h, and this was attributed to increased membrane conductance. In addition, treatment with 10 mM H(2)O(2) for 3 min produced immediate depolarization, which was due to decreased membrane conductance. The H(2)O(2)-induced hyperpolarization and depolarization were completely blocked by dithiothreitol, a disulfide-reducing agent. The later increase of membrane conductance induced by H(2)O(2) was completely blocked by 100 mM TEA, a K(+) channel blocker, suggesting that H(2)O(2)-induced hyperpolarization is due to the activation of K(+) conductance. However, the inhibition of K(+) efflux by TEA did not protect against H(2)O(2)-induced cell death in cultured Aplysia sensory neurons, which indicates that the signal pathway leading to H(2)O(2)-induced cell death is more complicated than expected.
Chang
Deok-Jin
DJ
National Research Laboratory of Neurobiology, Institute of Molecular Biology and Genetics, School of Biological Sciences, College of Natural Sciences, Seoul National University, San 56-1 Silim-dong Kwanak-gu, South Korea.
Lim
Chae-Seok
CS
Lee
Seung-Hee
SH
Kaang
Bong-Kiun
BK
D000818:Animals; D001048:Aplysia / Q000187:drug effects* / Q000502:physiology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009475:Neurons, Afferent / Q000187:drug effects* / Q000502:physiology; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000502:physiology*
D026902:Potassium Channel Blockers; D015221:Potassium Channels; D006861:Hydrogen Peroxide