Figure 1. The stimulatory effect of adenosine is Ca²⁺ dependent.

Single-fibre chemoreceptor activity recorded during steady-state control (left panel) and during exposure to 100 μM adenosine in the presence and absence of extracellular Ca²⁺ (middle panels) and after re-addition of Ca²⁺ (right panel). An example from one preparation is shown at the top, binned every 10 s and expressed in impulses s⁻¹. The inset at top left shows three superimposed action potentials. The mean +s.e.m. of five preparations is shown below. Superfusate P_O2 > 400 mmHg and P_CO2≈35 mmHg throughout.