ISSN:
1432-1424
Keywords:
Cl− channels
;
bilayers
;
PGO inhibition
;
Cl− dependence
;
open-time probability
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary We evaluated the effects of vawrying aqueous Cl− concentrations, and of the arginyl- and lysyl-specific reagent phenylglyoxal (PGO), on the properties of Cl− channels fused from basolaterally enriched renal medullary vesicles into planar lipid bilayers. The major channel properties studied were the anion selectivity sequence, anionic requirements for, channel activity. and the efects of varying Cl− concentrations and/or PGO on the relation between holding voltageV H -mV) and open-time probability (P o). Reducingcis Cl− concentrations, in the range 50–320mm, produced a linear reduction in fractional open time (P v) with a half-maximal reduction inP o atcis Cl−≈170mM. Channel activity was sustained by equimolar replacement ofcis Cl− with F−, but not with impermeant isethionate. Fortrans solutions, the relation between Cl− concentration andP 0 at 10mm Cl−. Reducingcis Cl− had no effect on the gating charge (Z) for channel opening, but altered significantly the voltage-independent, energy (δG) for channel opening. Phenylglyoxal (PGO) reducedZ and altered δG for Cl− channel activity when added tocis, but nottrans solutions, Furthermore, in the presence ofcis PGO, reducing thecis Cl− concentration had no effect onZ but altered δG. Thus we propose thatcis PGO and,cis Cl− concentrations affect separate sites determining channel activity at the extracellular faces of, these Cl− channels.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01868611
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