Figure 5.

Inhibition of adenosine-evoked I_K,ACh by extracellular ATP. (a) Chart records of whole-cell currents (Im) recorded at a holding potential of −40 mV and during voltage ramps applied before (1), and during exposure to 100 μM adenosine (2), and after further addition of 100 μM ATP (3 and 4). The rapid deflections in the current recording reflect the imposition of voltage-ramp protocols. (b) Superimposed I–V relationships measured during the voltage ramps applied at the points indicated by numerals (1–4) in (a). (c) Superimposed I–V relationships for the difference currents obtained by digital subtraction of current records as indicated.