Automated and manual patch clamp data of human induced pluripotent stem cell-derived dopaminergic neurons

Human induced pluripotent stem cells can be differentiated into dopaminergic neurons (Dopa.4U). Dopa.4U neurons expressed voltage-gated Na_V and K_V channels and showed neuron-like spontaneous electrical activity. In automated patch clamp measurements with suspended Dopa.4U neurons, delayed rectifier K⁺ current (delayed K_V) and rapidly inactivating A-type K⁺ current (fast K_V) were identified. Examination of the fast K_V current with inhibitors yielded IC₅₀ values of 0.4 mM (4-aminopyridine) and 0.1 mM (tetraethylammonium). In manual patch clamp measurements with adherent Dopa.4U neurons, fast K_V current could not be detected, while the delayed K_V current showed an IC₅₀ of 2 mM for 4-aminopyridine. The Na_V channels in adherent and suspended Dopa.4U neurons showed IC₅₀ values for tetrodotoxin of 27 and 2.9 nM, respectively. GABA-induced currents that could be observed in adherent Dopa.4U neurons could not be detected in suspended cells. Application of current pulses induced action potentials in approx. 70 % of the cells. Our results proved the feasibility of automated electrophysiological characterization of neuronal cells.