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 der ivatives) on the acetylcholine-induced luminescence of isolated arms and di ssociated 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 p otentiated acetylcholine-induced luminescence. The results with specific pu rinergic 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 cholinergi c system in Amphipholis squamata, there may be a purinergic system, acting in synergy with acetylcholine, and an inhibitory neuromodulatory catecholam inergic system, all associated with the control of luminescence.