Open AccessPHOTOREGULATION OF BIOLOGICAL ACTIVITY BY PHOTOCHROMIC REAGENTS, III. PHOTOREGULATION OF BIOELECTRICITY BY ACETYLCHOLINE RECEPTOR INHIBITORS
Author(s) -
Walter J. Deal,
Bernard F. Erlanger,
David Nachmansohn
Publication year - 1969
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.64.4.1230
Subject(s) - electrophorus , chemistry , photochromism , isomerization , biophysics , membrane potential , membrane , reagent , depolarization , chloride , stereochemistry , photochemistry , receptor , acetylcholine receptor , biochemistry , organic chemistry , torpedo , biology , catalysis
The photochromic compoundsN-p -phenylazophenyl-N -phenylcarbamylcholine chloride andp -phenylazophenyltrimethylammonium chloride inhibit the carbamylcholine-produced depolarization of the excitable membrane of the monocellular electroplax preparation ofElectrophorus . Thetrans isomer of each predominates in the light of a photoflood (420 mμ) lamp; they are stronger inhibitors than thecis isomers, which predominate under ultraviolet (320 mμ) irradiation. The potential difference across the excitable membrane may be photoregulated by exposing an electroplax in the presence of a solution of carbamylcholine and either of the two compounds to light of appropriate wavelengths, since light shifts thecis-trans equilibrium. The system may be considered as a model illustrating how one may link acis-trans isomerization, the first step in the initiation of a visual impulse, with substantial changes (20-30 mv) in the potential difference across an excitable membrane.