Figure 4. UTP-induced K⁺ currents.

A–C, K⁺ currents evoked by different concentrations of UTP were measured in perforated whole-cell configuration using gramicidin D and presented as current density (current/membrane capacitance of each cell). Holding potential was −40 mV. D, summary of total charge relative to 100 μm UTP. Total channel activity induced by UTP was estimated by integrating whole-cell currents for 10 min (‘total charge’). The dashed line in D denotes the value of the 100 μm UTP.