When whole urinary bladders of the toad were incubated with adenosine 3′,5′-monophosphate-3H (cyclic AMP-3H) > 95% of the radioactivity could be extracted from the tissue with trichloroacetic acid (TCA). The TCA-soluble radioactivity was separable by cation-exchange (Dowex-50) chromatography into residual cyclic AMP-3H, 5′-AMP-3H, adenosine diphosphate (ADP)-3H and inosine-3H. Thus, neither substantial tight binding of cyclic AMP to TCA-precipitable cell constituents nor any novel metabolite of cyclic AMP were found.
