Functional expression of potassium channels in cardiomyocytes derived from embryonic stem cells

S R Abtahi, H Sadraei, M Nematollahi, K Karbalaie, F Karamali, A Salamian, H Baharvand, M H Nasr-Esfahani

Abstract


Royan B1 stem cell can be differentiated to specialized cell types including cardiomyocytes. This developmental change is accompanied with expression of various K+ channel types. The aim of this study was to detect functional expression of K+ currents from stem cell stage and one week and two weeks after differentiation into cardiomyocyte. Mouse stem cell derived cardiomyocytes (ES-cardiomyocytes) were isolated to single cell suspension for K+current recording using whole cell patch-clamp technique. The predominant depolarizing current in ES-cardiomyocytes was a tetraethylammonium (TEA) (10 mM) sensitive current which was partially blocked by nifedipine (1 ┬ÁM) and attenuated by increasing concentration of EGTA (10 mM) in the pipette solution. Pharmacology and electrophysiological properties of this oscillatory sustained current very well matched with characteristics of Ca2+ activated K+ current. In addition there was another kind of sustained outward K+ current which was resistance to TEA but was inhibited by 3,4-diaminopyridine. The characteristic features of this current indicate that this current was due to activation of delayed rectifier K+ channels. RT-PCR study also confirmed expression of these two types of K+ channels in ES-cardiomyocytes. Therefore, present study shows functional expression of two types of K+ ionic current in ES-cardiomyocytes.


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