title: Low concentrations of ethanol but not of dimethyl sulfoxide (DMSO) impair reciprocal retinal signal transduction.
abstract: BACKGROUND
  The model of the isolated and superfused retina provides the opportunity to test drugs and toxins. Some chemicals have to be applied using low concentrations of organic solvents as carriers. Recently, E-/R-type (Cav2.3) and T-type (Cav3.2) voltage-gated Ca(2+) channels were identified as participating in reciprocal inhibitory retinal signaling. Their participation is apparent, when low concentrations of NiCl2 (15 μM) are applied during superfusion leading to an increase of the ERG b-wave amplitude, which is explained by a reduction of amacrine GABA-release onto bipolar neurons. During these investigations, differences were observed for the solvent carrier used.
  
  
  METHODS
  Recording of the transretinal receptor potentials from the isolated bovine retina.
  
  
  RESULTS
  The pretreatment of bovine retina with 0.01 % (v/v) dimethylsulfoxide did not impair the NiCl2-mediated increase of the b-wave amplitude, which was 1.31-fold ± 0.03 of initial value (n = 4). However, pretreatment of the retina with the same concentration of ethanol impaired reciprocal signaling (0.96-fold ± 0.05, n = 4). Further, the implicit time of the b-wave was increased, suggesting that ethanol itself but not DMSO may antagonize GABA-receptors.
  
  
  CONCLUSIONS
  Ethanol itself but not DMSO may block GABA receptors and cause an amplitude increase by itself, so that reciprocal signaling is impaired.
authors.affiliation: Institute of Neurophysiology, University of Cologne, Robert-Koch-Str. 39, D-50931, Köln, Germany.|Department of Ophthalmology, RWTH Aachen University, Pauwelsstr. 30, D-52074, Aachen, Germany.
authors.forename: Siarhei A
authors.initials: SA
authors.lastname: Siapich
authors.affiliation: Institute of Neurophysiology, University of Cologne, Robert-Koch-Str. 39, D-50931, Köln, Germany.
authors.forename: Isha
authors.initials: I
authors.lastname: Akhtar
authors.affiliation: Institute of Neurophysiology, University of Cologne, Robert-Koch-Str. 39, D-50931, Köln, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hescheler
authors.affiliation: Institute of Neurophysiology, University of Cologne, Robert-Koch-Str. 39, D-50931, Köln, Germany. toni.schneider@uni-koeln.de.
authors.forename: Toni
authors.initials: T
authors.lastname: Schneider
authors.affiliation: Institute of Neurophysiology, University of Cologne, Robert-Koch-Str. 39, D-50931, Köln, Germany.|University Eye Hospital, University of Lübeck, Ratzeburger Allee 160, D-23538, Lübeck, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Lüke
mesh_terms: D000818:Animals; D020908:Calcium Channels, R-Type / Q000502:physiology; D020747:Calcium Channels, T-Type / Q000502:physiology; D002417:Cattle; D004121:Dimethyl Sulfoxide / Q000008:administration & dosage*; D004596:Electroretinography / Q000187:drug effects*; D000431:Ethanol / Q000008:administration & dosage*; D058787:GABA-A Receptor Antagonists / Q000008:administration & dosage; D009532:Nickel / Q000494:pharmacology; D010775:Photic Stimulation; D012160:Retina / Q000187:drug effects* / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D012997:Solvents / Q000008:administration & dosage*
chemical_list: D020908:Calcium Channels, R-Type; D020747:Calcium Channels, T-Type; D058787:GABA-A Receptor Antagonists; D012997:Solvents; D000431:Ethanol; C022838:nickel chloride; D009532:Nickel; D004121:Dimethyl Sulfoxide
keywords: Cav2.3; Pharmacoresistant voltage-gated Ca2+ channels; R-type; Reciprocal inhibition