A, concentration-dependent polarisations of sensor in response to exogenous adenosine (1.25-20 μM) applied for the duration shown by the black bar and between upward deflections of chart event marker. The selective adenosine deaminase inhibitor, coformycin (1 μM), greatly attenuated the adenosine-dependent polarisation. B, graph of the experiment depicted in A showing linearity of sensor to adenosine over the concentration range most commonly encountered in this study, with the effects of coformycin on the adenosine signal.