Fig. 9. Haemolymph concentration of dopamine (A), serotonin (B) and octopamine (C) before (t₀), during (t_2.5–t₁₀) and after (t_12.5–t₃₀) the perfusion of a solution of 2.4 nmol min^–1 g^–1 body mass of adenosine. The vertical dotted lines indicate the infusion period. Data are presented as means ± s.d. (N=5).