“4 The stimulation of C fibres by Ado was significantly attenuated by pretreatment with aminophylline , a non‐selective Ado receptor antagonist, was completely prevented by 1,3‐dipropyl‐8‐cyclopentylxanthine, an Ado A1 receptor antagonist, but was unaffected by 3,7‐dimethy‐1‐propargylxanthine, an A2 receptor antagonist.”