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Using gadolinium to identify stretch-activated channels: technical considerations
R A Caldwell1, H F Clemo, C M Baumgarten
1Department of Physiology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia 23298, USA.
The American Journal of Physiology
|August 4, 1998
Summary
Gadolinium (Gd3+) is used to study stretch-activated ion channels (SACs), but its effectiveness is limited. Factors like anion binding can reduce free Gd3+ concentrations, potentially leading to inaccurate conclusions about SAC involvement.
Area of Science:
- Physiology
- Biophysics
- Pharmacology
Background:
- Gadolinium (Gd3+) is widely used to inhibit cation-selective stretch-activated ion channels (SACs).
- Gd3+ sensitivity is a common method to infer SAC involvement in physiological and pathophysiological processes.
- The interpretation of Gd3+ experiments requires careful consideration of experimental conditions.
Purpose of the Study:
- To highlight the limitations of using Gd3+ as a sole indicator of SAC activity.
- To discuss factors that can confound the interpretation of Gd3+ experiments.
- To provide guidance for the accurate use and interpretation of Gd3+ in SAC research.
Main Methods:
- Review of existing literature on Gd3+ and SACs.
- Analysis of the chemical interactions between Gd3+ and common buffer components (e.g., phosphate, bicarbonate, EGTA).
- Discussion of the implications of these interactions for experimental outcomes.
Main Results:
- Gd3+ avidly binds to anions in physiological solutions, significantly reducing free Gd3+ concentrations.
- Low free Gd3+ concentrations can lead to false-negative results, suggesting no SAC involvement when it is present.
- Certain SACs are inherently insensitive to Gd3+, and Gd3+ can also block other ion channels, leading to potential false positives.
Conclusions:
- Gd3+ remains a valuable tool for studying SACs, but its use requires careful experimental design.
- Researchers must account for Gd3+ binding to anions to avoid misinterpreting results.
- Awareness of Gd3+ insensitivity in some SACs and off-target effects is crucial for accurate conclusions.