Aims: 

The mouse is the preferred model organism for genetic manipulation. The fact that different mouse strains exhibit considerable distinctions in phenotype needs to be taken into account when designing studies using knock out mice. In particular, differences in the genetic background of wild type and genetically manipulated animals may introduce artificial effects independent of the genetic manipulation itself. Phenotype differences between mouse strains, for example, exist in cardiac electrophysiology. Detailed studies on ion channel expression and/or function in excitable cells originating from various mouse strains, however, are still lacking. Here, we compared voltage-gated sodium channel function between skeletal myocytes obtained from different frequently used mouse strains (C57BL/6, SV129 and FVB).

Methods: 

Primary skeletal myocyte cultures were generated from neonatal and adult mice, and their sodium current properties were detected by using the whole cell patch clamp technique after defined culture time periods.

Results: 

The voltage-dependencies of sodium current activation and inactivation were significantly different in skeletal myocytes isolated from various mouse strains. Differences also existed in the kinetics of fast inactivation and in the sensitivities to block by tetrodotoxin. In addition, the sodium current properties of skeletal myocytes isolated from neonatal mice differed from those derived from adult mice.

Conclusion: 

The sodium current properties of primary skeletal myocytes are mouse strain-dependent. This may be explained by differences in sodium channel isoform expression. Our findings will have to be taken into account when designing studies to investigate electrophysiological phenotypes of genetically manipulated mouse models. Supported by Austrian FWF (P19352-B11).