title: H2O2augments cytosolic calcium in nucleus tractus solitarii neurons via multiple voltage-gated calcium channels.
abstract: Reactive oxygen species (ROS) play a profound role in cardiorespiratory function under normal physiological conditions and disease states. ROS can influence neuronal activity by altering various ion channels and transporters. Within the nucleus tractus solitarii (nTS), a vital brainstem area for cardiorespiratory control, hydrogen peroxide (H2O2) induces sustained hyperexcitability following an initial depression of neuronal activity. The mechanism(s) associated with the delayed hyperexcitability are unknown. Here we evaluate the effect(s) of H2O2on cytosolic Ca2+(via fura-2 imaging) and voltage-dependent calcium currents in dissociated rat nTS neurons. H2O2perfusion (200 µM; 1 min) induced a delayed, slow, and moderate increase (~27%) in intracellular Ca2+concentration ([Ca2+]i). The H2O2-mediated increase in [Ca2+]iprevailed during thapsigargin, excluding the endoplasmic reticulum as a Ca2+source. The effect, however, was abolished by removal of extracellular Ca2+or the addition of cadmium to the bath solution, suggesting voltage-gated Ca2+channels (VGCCs) as targets for H2O2modulation. Recording of the total voltage-dependent Ca2+current confirmed H2O2enhanced Ca2+entry. Blocking VGCC L, N, and P/Q subtypes decreased the number of cells and their calcium currents that respond to H2O2The number of responder cells to H2O2also decreased in the presence of dithiothreitol, suggesting the actions of H2O2were dependent on sulfhydryl oxidation. In summary, here, we have shown that H2O2increases [Ca2+]iand its Ca2+currents, which is dependent on multiple VGCCs likely by oxidation of sulfhydryl groups. These processes presumably contribute to the previously observed delayed hyperexcitability of nTS neurons in in vitro brainstem slices.
authors.affiliation: Department of Physiology, Kirksville College of Osteopathic Medicine, A.T. Still University of Health Sciences, Kirksville, Missouri.|Department of Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri.
authors.forename: Tim D
authors.identifier: http://orcid.org/0000-0001-8596-6311
authors.initials: TD
authors.lastname: Ostrowski
authors.affiliation: Department of Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri.
authors.forename: Heather A
authors.initials: HA
authors.lastname: Dantzler
authors.affiliation: Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri; and.
authors.forename: Luis
authors.identifier: http://orcid.org/0000-0002-5221-6060
authors.initials: L
authors.lastname: Polo-Parada
authors.affiliation: Department of Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri klinedd@missouri.edu.
authors.forename: David D
authors.identifier: http://orcid.org/0000-0003-3269-0184
authors.initials: DD
authors.lastname: Kline
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000008:administration & dosage*; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D008297:Male; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D017552:Solitary Nucleus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*
chemical_list: D015220:Calcium Channels; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D002118:Calcium
keywords: ROS; autonomic nervous system; redox signaling; voltage-gated calcium channel