A, an example of outward currents obtained during 300 ms pulses to membrane potentials between -90 and +30 mV from a holding potential of -70 mV in control conditions, and in the presence of 5 mM 4-AP both in the absence and presence of 10 μM adenosine. B, mean ±s.e.m. current density-voltage relations obtained in control conditions (•, n = 10), in the presence of 5 mM 4-AP (○, n = 10) and in the last condition but with 10 μM adenosine (×, n = 3).