RELAXANT EFFECT OF CYCLIC ADENOSINE 3', 5' -MONOPHOSPHATE ON THE ISOLATED RABBIT ILEUM

¹ Department of Medicine, Brooklyn-Cumberland Medical Center, State University of New York, Downstate Medical Center, Brooklyn, New York

The effects of epinephrine, cyclic adenosine 3', 5' -AMP and other adenine nucleotides were investigated in segments of isolated rabbit ileum before and after adrenergic blockade by phentolamine and MJ 1999. 3', 5' -AMP, adenosine, 5' -AMP, 2', 3'-AMP and ATP all inhibited spontaneous motility of the isolated ileum within seconds, before and after adrenergic receptor blockade. The concentration of 3', 5'-AMP used to decrease the amplitude of contraction was between 10^-6 and 10^-4 M. There was evidence of tachyphylaxis. The depression of motility by 3', 5' -AMP was qualitatively similar to that observed with epinephrine and the other adenine nucleotides. Alpha and beta receptors did not appear to be involved in the function of intestinal relaxation induced by 3', 5' -AMP or other adenine nucleotides. The data obtained with the adenine nucleotides suggest a nonspecific role of 3', 5' -AMP on intestinal motility. The adenosine moiety may be the active inhibitory agent.