Effects of catecholamines and purines on luminescence in the brittlestar Amphipholis squamata (Echinodermata).

The effects of catecholamines (dopamine, adrenaline, noradrenaline and its derivatives), 5-hydroxytryptamine and purines (adenosine, ATP and their derivatives) on the acetylcholine-induced luminescence of isolated arms and dissociated photocytes of the luminescent ophiuroid Amphipholis squamata were tested. The results showed that catecholamines and 5-hydroxytryptamine (10(-)(5) to 10(-)(3 )mol l(-)(1)) had a strong dose-dependent inhibitory effect on acetylcholine-induced luminescence. In contrast, purines (10(-)(4) and 10(-)(3 )mol l(-)(1)) triggered luminescence in the absence of acetylcholine and/or potentiated acetylcholine-induced luminescence. The results with specific purinergic agonists and antagonists indicated the involvement of P(1)- and P(2)-like purinoceptors in the control of luminescence. Our study suggests that, in addition to the previously described cholinergic system in Amphipholis squamata, there may be a purinergic system, acting in synergy with acetylcholine, and an inhibitory neuromodulatory catecholaminergic system, all associated with the control of luminescence.