[Identification of pacemaker cells from atrial natriuretic peptide expressing embryonic stem cells]

At present there exists a limited understanding of mechanisms of differentiation and specialization of cardiac conduction system in mammals. For characterization of its development and differentiation on early stages we used as experimental model murine embryonic stem cells expressing enhanced green fluorescent protein (eGFP) under transcriptional control of human atrial natriuretic peptide (ANP) as promoter. Cardiac nature of ANP-eGFP was confirmed by immuno staining with antibodies to troponin I and a-actinin. In ANP- eGFP expressing embryonic stem cells it is possible to distinguish subpopulation of spindle-shaped pacemaker cells capable to higher frequency of spontaneous contractions, velocity of activation and amplitude compared with those of triangular and polygonal atrial-like cardiomyocytes. These results show that expression of ANP-eGFP cells allows to identify pacemaker cells among embryonic stem cells by their morphological and electrophysiological properties.