Distribution of Cyclic Adenosine Monophosphate in Rat Brain

Cyclic 3',5'-adenosine monophosphate (AMP) was assayed by converting it enzymatically to adenosine triphosphate (ATP) with phosphodiesterase, myokinase, and pyruvate kinase. Adenosine triphosphate was measured in a liquid scintillation spectrometer from the photons emitted when ATP serves as a substrate of the firefly luciferin-luciferase system. In the rat, the highest concentrations of cyclic AMP (35μμmols to 58μμmols protein) were found in the pituitary and pineal glands and in cerebellum; intermediate levels (19μμmols to 25μμmols/gm protein) were found in spinal cord, thalamus, hypothalamus, telencephalon, and olfactory bulb; the lowest concentrations (11μμmols to 15μμmols/ mg protein) were found in corpora quadrigemina, olfactory tubercle, caudate, hippocampus, pons, and medulla. Studies of the subcellular distribution of cyclic AMP showed that virtually all the cyclic AMP was bound to particulate material associated with the nuclear and mitochondrial fractions. of brain homogenates.