Oxidation regulates cloned neuronal voltage-dependent Ca2+ channels expressed in Xenopus oocytes.
Functional modifications of neuronal P/Q-type voltage-dependent Ca2+ channels expressed in Xenopus oocytes by oxidation were examined electrophysiologically. Oxidation by external H2O2 enhanced the whole-oocyte currents through the Ca2+ channels composed of the alpha1A, alpha2/delta, and beta3 subunits at negative voltages (<0 mV) without markedly affecting the currents at more positive voltages. Single-channel analysis showed that oxidation accelerates the overall channel opening process. The effect of H2O2 to enhance the Ca2+ channel activity did not require heterologous expression of the alpha2/delta subunit, and it was not mimicked by a cysteine-specific oxidizing agent. The results suggest that oxidative stress may regulate the activity of neuronal Ca2+ channels and that regulation by oxidation may be important in some clinical situations, such as in reperfusion injury after ischemic episodes.
Li
A
A
Department of Physiology and Biophysics, Bowen 5660, The University of Iowa, Iowa City, Iowa 52242, USA.
Ségui
J
J
Heinemann
S H
SH
Hoshi
T
T
D000818:Animals; D015220:Calcium Channels / Q000187:drug effects*; D003001:Cloning, Molecular; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D009865:Oocytes / Q000187:drug effects* / Q000378:metabolism; D010084:Oxidation-Reduction; D018408:Patch-Clamp Techniques; D011725:Pyridines / Q000494:pharmacology*; D013439:Sulfhydryl Reagents; D014981:Xenopus
D015220:Calcium Channels; D011725:Pyridines; D013439:Sulfhydryl Reagents; C011801:2,2'-dithiobis(5-nitropyridine); D006861:Hydrogen Peroxide