Background:　The　studies　have　found　that　the　tetrodotoxin-sensitive　sodium　channels　exist　in　various　human　and　animal　mesenchymal　stem　cells,　but　whether　sodium　channels　may　influence　the　differentiation　of　mesenchymal　stem　cells　into　myocardial　cells　has　not　been　confirmed.　Objective:　To　observe　the　effect　of　sodium　channel　blocker　tetrodotoxin　on　the　differentiation　of　mesenchymal　stem　cells　into　cardiac-like　cells.　Methods:　Rat　bone　marrow　mesenchymal　stem　cells　were　isolated　with　Percoll＇s　density　gradient　centrifugation　and　differential　adhesion　method,　and　then　the　adult　rat　myocardial　cells　were　isolated　by　aorta　retrograde　collagenase　perfusion;　rat　bone　marrow　mesenchymal　stem　cells　labeled　with　4＇,6-diamidino-2-phenylindole　were　co-cultured　with　adult　rat　myocardial　cells,　and　induced　with　0,　10　and　100　μmol/L　tetrodotoxin;　and　then　the　differentiation　of　bone　marrow　mesenchymal　stem　cells　into　cardiac-like　cells　was　observed　at　1　week　after　induction.　Results　and　Conclusion:　Immunofluorescence　staining　showed　that　the　bone　marrow　mesenchymal　stem　cells　could　express　cardiac-specific　protein　desmin　and　myosin　after　bone　marrow　mesenchymal　stem　cells　co-cultured　with　myocardial　cells　for　1　week,　while　10　and　100　μmol/L　tetrodotoxin　could　inhibit　the　expressions　of　desmin　and　myosin　in　bone　marrow　mesenchymal　stem　cells.　The　results　indicate　that　sodium　channel　may　play　a　pivotal　role　in　the　differentiation　of　bone　marrow　mesenchymal　stem　cells　into　cardiac-like　cells.