Assessment of potassium current in Royan B1 stem cell derived cardiomyocytes by patch-clamp technique

Embryonic stem cells are capable of differentiating to variety of cell tissues including cardiomyocytes. This developmental change is accompanied with a great deal of ion channel expression and functions. Mouse stem cell derived cardiomyocytes were prepared and separated to yield isolated single cell suspension for cell current recording. In the present study some properties of the K+-current in Royan B1 stem cell derived cardiomyocytes were investigated using whole cell patch-clamp technique. When the holding potential was -60 mV, in some cells a major outward current was elicited by square depolarizing pulses from -60 mV to +50 mV. This outward current was sustained for the duration of 300 ms test pulse. The sustained outward K+ current was inhibited by tetraethylammonium (10 mM) indicating the activity of Ca2+ activated K+ channel in these cells. In some of the cells with 0.2 mM 3,ethylene glycol-bis (β-aminoethyl ether) N,N,N`,N`-tetraacetic acid in the pipette, only a very small outward current was recorded which suggests that in these cells the voltage activated K+ channels is either absent or if existed it is not fully functional. Other cells were in far between, indicating that voltage activated K+ channels are developing in these cells but it is not yet fully functional. In conclusion, we have identified functional large conductance Ca2+ activated K+ channel in Royan B1 stem cell derived cardiomyocytes.