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Knockout mice for pharmacological screening: testing the specificity of Na+-Ca2+ exchange inhibitors
Hannes Reuter1, Scott A Henderson, Tieyan Han
1Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, Calif 90095-1760, USA.
Abstract:
The role of the Na+-Ca2+ exchanger as a major determinant of cell Ca2+ is well defined in cardiac tissue, and there has been much effort to develop specific inhibitors of the exchanger. We use a novel system to test the specificity of two putative specific inhibitors, KB-R7943 and SEA0400. The drugs are applied to electrically stimulated heart tubes from control mouse embryos or embryos with the Na+-Ca2+ exchanger knocked out. We monitored effects of the drugs on Ca2+ transients. Both drugs depress the Ca2+ transients at low concentrations even in the absence of any Na+-Ca2+ exchanger. KB-R7943 and SEA0400 are not completely specific and should be used with caution as Na+-Ca2+ exchange inhibitors.
Insights
Two common Na+-Ca2+ exchanger inhibitors, KB-R7943 and SEA0400, are not specific. They affect calcium transients even without the target exchanger, requiring cautious use in research.
Area of Science:
- Cardiovascular Physiology
- Molecular Pharmacology
- Ion Transport Mechanisms
Background:
- The Na+-Ca2+ exchanger (NCX) is crucial for regulating intracellular calcium in cardiac cells.
- Developing specific NCX inhibitors is a key research goal for understanding cardiac function and disease.
- Previous studies suggested KB-R7943 and SEA0400 as specific NCX inhibitors.
Purpose of the Study:
- To evaluate the specificity of the putative NCX inhibitors KB-R7943 and SEA0400.
- To determine if these drugs exhibit inhibitory effects independent of the Na+-Ca2+ exchanger.
Main Methods:
- Utilized a novel experimental system involving electrically stimulated heart tubes from wild-type and Na+-Ca2+ exchanger knockout mouse embryos.
- Administered KB-R7943 and SEA0400 at varying concentrations.
- Monitored and analyzed the impact of drug application on intracellular calcium (Ca2+) transients.
Main Results:
- Both KB-R7943 and SEA0400 demonstrated significant depression of Ca2+ transients at low concentrations.
- This inhibitory effect was observed even in heart tubes lacking the Na+-Ca2+ exchanger.
- Indicating a lack of complete specificity for the target exchanger.
Conclusions:
- KB-R7943 and SEA0400 are not entirely specific inhibitors of the Na+-Ca2+ exchanger.
- Researchers should exercise caution when using these compounds as specific pharmacological tools for studying NCX.
- Further investigation into off-target effects is warranted for these commonly used agents.