Electrophysiological properties of human β-cell lines EndoC-βH1 and -βH2 conform with human β-cells
Hastoy B., Godazgar M., Clark A., Nylander V., Spiliotis I., van de Bunt M., Chibalina M., Barrett A., Burrows C., Tarasov A., Scharfmann R., Gloyn AL., Rorsman P.
<jats:title>Abstract</jats:title><jats:p>The electrophysiological and secretory properties of the human β-cell lines EndoC-βH1 and EndoC-βH2 were investigated. Both cell lines respond to glucose (6-20mM) with 2-to 3-fold stimulation of insulin secretion, an effect that was mimicked by tolbutamide (0.2mM) and reversed by diazoxide (0.5mM). Glucose-induced insulin release correlated with an elevation of [Ca<jats:sup>2+</jats:sup>]<jats:sub>i</jats:sub>, membrane depolarization and increased action potential firing. K<jats:sub>ATP</jats:sub> channel activity at 1mM glucose is low and increasing glucose to 6 or 20mM reduced K<jats:sub>ATP</jats:sub> channel activity to the same extent as application of the K<jats:sub>ATP</jats:sub> channel blocker tolbutamide (0.2mM). The upstroke of the action potentials in EndoC-βH1 and −βH2 cells observed at high glucose principally reflects activation of L- and P/Q-type Ca<jats:sup>2+</jats:sup> channels with some small contribution of TTX-sensitive Na<jats:sup>+</jats:sup> channels. Action potential repolarization involves activation of voltage-gated Kv2.2 channels and large-conductance Ca<jats:sup>2+</jats:sup>-activated K<jats:sup>+</jats:sup> channels. Exocytosis (measured by measurements of membrane capacitance) was triggered by membrane depolarizations >10ms to membrane potentials above -30mV. Both cell lines were well-granulated (6,000-15,000 granules/cell) and granules consisted of a central insulin core surrounded by a clear halo. We conclude that the EndoC-βH1 and -βH2 cells share many features of primary human β-cells and that they represent a useful experimental model.</jats:p>