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Modification of Cl − transport in skeletal muscle of Rana temporaria with the arginine‐binding reagent phenylglyoxal
Author(s) -
Skydsgaard Jørgen M.
Publication year - 1998
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.1998.591bk.x
Subject(s) - phenylglyoxal , chemistry , conductance , biophysics , arginine , membrane , membrane potential , reagent , ouabain , permeability (electromagnetism) , rana , sodium , chromatography , analytical chemistry (journal) , biochemistry , amino acid , anatomy , biology , organic chemistry , mathematics , combinatorics
1 The effect of membrane modification by the arginine‐binding reagent phenylglyoxal (PG) on Cl − permeability was studied in thin bundles of twitch fibres from frog muscle. The bundles were modified by a method that yields stable PG binding to outer arginyl residues in erythrocyte membranes. 2 PG almost eliminated the pH‐dependent fraction of 36 Cl − efflux under conditions of Cl − equilibrium in depolarized bundles: the fluxes at pH 7.2 and 8.5 were strongly inhibited approaching an apparent baseline value close to the normal flux at pH 6 which per se was not inhibited. 3 The uninhibited flux at pH 6 in modified bundles maintained the normally high sensitivity to DNDS), and the reduction of fluxes at pH > 7 coincided with increased DNDS sensitivity, suggesting a selective blocking of the pH‐dependent flux fraction that has a low DNDS sensitivity. 4 In normal Ringer solution the modified fibres showed normal resting membrane potentials ( V m ) with normal sensitivity to [K + ] o but sensitivity to changes of [Cl − ] o was almost eliminated, suggesting a normal resting Na + : K + conductance ratio ( g Na / g K ) and that the main influence of modification on the resting membrane conductance ( g m ) was a loss of Cl − conductance ( g Cl ). 5 The modified fibres were not excitable, possibly due to arginine modification in the voltage sensor (S4) of the Na + channels. 6 These results suggest that positively charged arginines are important for the activity of the pH‐dependent V m ‐stabilizing Cl − channels and that PG may isolate a pH‐independent ‘basal’ flux fraction which normally dominates the Cl − flux at low pH.