Abstract
Telocytes (TCs) with exceptionally long cellular processes of telopodes have been described in human epicardium to act as structural supporting cells in the heart. We examined myocardial chamber-specific TCs identified in atrial and ventricular fibroblast culture using immunocytochemistry and studied their electrophysiological property by whole-cell patch clamp. Atrial and ventricular TCs with extended telopodes and alternating podoms and podomers that expressed CD34, c-Kit and PDGFR-β were identified. These cells expressed large conductance Ca2+-activated K+ current (BKCa) and inwardly rectifying K+ current (IKir), but not transient outward K+ current (Ito) and ATP-sensitive potassium current (KATP). The active channels were functionally competent with demonstrated modulatory response to H2S and transforming growth factor (TGF)-β1 whereby H2S significantly inhibited the stimulatory effect of TGF-β1 on current density of both BKCa and IKir. Furthermore, H2S attenuated TGF-β1-stimulated KCa1.1/Kv1.1 (encode BKCa) and Kir2.1 (encode IKir) expression in TCs. Our results show that functionally competent K+ channels are present in human atrial and ventricular TCs and their modulation may have significant implications in myocardial physiopathology.
Highlights
Telocytes (TC) are newly identified cells that are found in the interstitial space of many organs, including heart [1], bladder [2], lungs [3] and skeletal muscle [4] and intimately contacting the parenchymal tissues
We have recently showed that hydrogen sulphide (H2S) modulated the activity of ion channels in human atrial fibroblasts and suppressed their transformation into myofibroblasts in response to transforming growth factor (TGF)-b1
In accordance with previous reports [1, 8, 20], these human TCs stained positive for CD34, c-Kit (CD34/c-Kit double staining in Fig. S1) and PDGF receptor (PDGFR)-b markers (Fig. 1)
Summary
Telocytes (TC) are newly identified cells that are found in the interstitial space of many organs, including heart [1], bladder [2], lungs [3] and skeletal muscle [4] and intimately contacting the parenchymal tissues. They have previously been described as interstitial Cajal-like cells in atrial and ventricular myocardium [5, 6] and very little was known of their function. We present first evidence of electrophysiological properties of human TCs derived from atrial and ventricular myocardium and demonstrate the modulatory role of H2S on the ion channel activity
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