Properties of single outwardly rectifying Cl- channels in heart.
Key result
In rabbit atrial cell membranes, single Cl- channels showed strong outward rectification, a unitary conductance of 60 +/- 3 pS, and were reversibly inhibited by DIDS and SITS.
Population
Inside-out patches from rabbit atrial cell membranes (n=155 patches)
Comparison
Application of Cl- transport blockers DIDS and… vs Baseline symmetrical Cl- conditions
Design
Preclinical
Authors
Discussion
Loading...
Member takes
Implication
Characterizes rabbit atrial Cl- channels at single-channel level; leaves open their human electrophysiologic role and therapeutic potential.
Key Points
- Identify and characterize the single-channel electrical properties and pharmacological sensitivity of outwardly rectifying chloride channels in cardiac cell membranes.
- Applied the inside-out patch-clamp technique to rabbit atrial cell membranes (N=155 patches) under symmetrical chloride conditions configured to suppress cation currents.
- Assessed channel ion selectivity by substituting cations with N-methyl-D-glucamine and chloride with methanesulfonate, alongside bath application of disulfonic stilbene blockers (100 µmol/L DIDS and 1 mmol/L SITS).
- Single-channel activity was detected in 14 of 155 patches (9%), demonstrating strong outward rectification and a unitary conductance of 60 ± 3 pS at positive voltages.
- Channel activity was unaffected by cation replacement, shifted as predicted for chloride selectivity upon anion replacement, and was reversibly blocked with flickering by DIDS and SITS.
- Ensemble-average currents displayed no time dependence and closely resembled macroscopic cardiac background chloride currents.
Structured PICO
P
Population
In vitro patch-clamp study of 155 inside-out patches from rabbit atrial cell membranes.
I
Intervention
Application of Cl- transport blockers DIDS (100 mumol/L) and SITS (1 mmol/L) and ion substitution
C
Comparator
Baseline symmetrical Cl- conditions
O
Outcome
Single-channel activity and electrophysiological properties (unitary conductance, current-voltage relation)surrogate
The study identifies and characterizes single outwardly rectifying Cl- channels in rabbit atrial cells, providing a single-channel equivalent for macroscopic background Cl- currents in the heart.
Cite This Study
Duan et al. (1994) studied this question. Cl- transport blockers DIDS and SITS was evaluated on Single-channel activity and properties. In rabbit atrial cell membranes, single Cl- channels showed strong outward rectification, a unitary conductance of 60 +/- 3 pS, and were reversibly inhibited by DIDS and SITS.