Figure 3

Performance of patch-clamp recordings from Merkel cells in whisker hair follicle preparation. A) Schematic diagram shows the setting of patch-clamp recording electrode with a dual pressure system. The recording electrode is connected to a 50-ml glass syringe and also to a high-speed pressure-clamp device (HSPC). The syringe is used to deliver a high pressure into the electrode when the electrode is approaching a targeted Merkel cell. The high pressure, generated by compressing 5 ml air in the syringe, is used to clean the surface of Merkel cell layer. The HSPC is used to deliver a lower positive pressure (~80 mmHg) during final touch of Merkel cell membranes with the recording electrode. The HSPC is also used for delivering a negative pressure during the formation of membrane seal and whole-cell configuration. B) Two images show the Merkel cell layer before (top) and following (bottom) the application of a high positive pressure into the recording electrode through the syringe. The recording electrode is placed near the Merkel cell layer (star indicated). Individual cells can be clearly seen following the high pressure. C) Illustration of membrane capacitive transient in the seal test (5 mV pulses) under the following configurations: after the formation of GΩ seal and in cell attached (c/a) configuration (left), and after breaking into whole-cell configuration (right). Vh = −70 mV. D) Sample traces of voltage-gated currents recorded from a Merkel cell under the whole-cell voltage-clamp mode. Vh = −70 mV. Voltage steps were applied at an increment of 20 mV from −90 mV to +50 mV. E) Sample traces of membrane depolarization and action potential firing in the same Merkel cell under the whole-cell current-clamp mode. Current steps were applied at an increment of 20 pA from −40 pA to +80 pA. The cell had a resting membrane potential of −50 mV.