Figure 2. Concentration dependence of the amplitudes of the ATP-evoked currents.

The cells were held at −40 mV and fast application of ATP (30 nm to 100 μm) was done with a puffer pipette next to the cell. Amplitudes of the ATP currents were measured at the peak of the responses and were expressed as current densities. Due to the fast desensitization of the ATP-evoked activation of the cation currents, only the responses to the first application of ATP were measured. As the concentration-response relationship was obtained on 8 different cell preparations, the responses were normalized to that of 100 μm ATP on the same day. Results are expressed as the mean ± s.e.m. and each point is the average of 3–8 responses.