Abstract: | Effects of cyclic nucleotides on motile iridophores were examined in the blue damselfish, Chrysiptera cyanea. All of the cyclic nucleotides tested, i.e. cAMP, 2',3'-cAMP and cGMP, accelerated the clearing response of the cells even at concentrations of 10(-5) or 10(-4) M. The action of these nucleotides was effectively antagonized by methylxanthines. These results suggest that the effect of cyclic nucleotides on damselfish iridophores is mediated by adenosine receptors in a similar fashion to the action of adenosine. |